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- TexaSoft's
- USING KWIKSTAT 4.1
- Reference Guide, Condensed Disk Version
-
- (C)Copyright 1995 Alan C. Elliott
-
- (C)Copyright 1991, 92, 93, 94, 95 Alan C. Elliott For additional
- information on this product, contact TexaSoft, P.O. Box 1169, Cedar
- Hill, Texas 75106-1169 (214) 291-2115, Fax: (214) 291-3400,
- Compuserve:70721,3145, Internet: 70721.3145@compuserve.com. Production
- team: Alan Elliott, Marcia Stoesz, Paul Witt, Nancy Witt, Carol
- Bigler, Doug Pollock, Melanie Walker. Program Testing Team: Leo Bolta,
- Shopsy's Foods, Canada Randy Hamlin, Senior Scientist, R&D Dept.,
- Hunt-Wesson, Inc. Dick Hawkins, Hunt-Wesson, Inc. Jack Holloway III,
- University of Phoenix Robert Jirsa, Southern CT State University Chip
- Kloos, Lab Manager, R&D Dept., Hunt-Wesson, Inc. Victor L. Landry,
- Ph.D., The Mercy Hospital of Pittsburgh, PA Gerard Leboucher,Labo
- Ethologie Et Psychoph, France Allen Lein, Professor Emeritus, UCSD
- Randolph Maheux, Tampa, FL Sukanya Misra, SMU Sanford Moos, Lab
- Manager, Enzo Labs Joseph Padgett, Raleigh, NC George Sadler, Ph.D.,
- USC Prof. Emeritus, Okla. City, OK Dr. Karl-August Schaeffer, Cologne,
- Germany Michael Stratil, Ph. D., Pembroke State University Wayne
- Woodward, Ph. D., SMU Carter Yeager, Boston University
-
- All rights reserved. No part of this book may be reproduced without
- prior permission. For information, address TexaSoft, P.O. Box 1169,
- Cedar Hill, Texas 75106-1169.
-
- No patent liability is assumed with respect to the use of the
- information contained herein. While every precaution has been taken in
- the preparation of this publication, the publisher assumes no
- responsibility for errors or omissions. Neither is any liability
- assumed for damages resulting from the use of the information herein.
-
- The KWIKSTAT software and manual ("documentation") are copyrighted by
- TexaSoft and are protected by both United States copyright and
- International treaty provisions. Before you can use this program on an
- on-going basis, you must pay a license fee. An order form is on disk
- in the file named KSORDER.TXT
-
- Important Information in the file LATENEWS.DOC: On the KWIKSTAT disk
- is a file named LATENEWS.DOC, which contains information about the
- program that is not in this documentation.
-
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 1
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- ===========================
- AN OVERVIEW OF KWIKSTAT 4.1
- ===========================
-
- KWIKSTAT is a statistical data analysis program. It was designed by
- professional statistical consultants and researchers to allow you to
- quickly and easily use the most commonly needed statistical data
- analysis procedures and graphs.
-
- KWIKSTAT REQUIREMENTS
-
- KWIKSTAT is a DOS program and may be run as either a stand alone
- application, or as a DOS window executed from within the "Windows"
- operating environment. It requires PC-DOS or MS-DOS version 3.0 or
- higher. If you are running Windows, version 3.1 or higher is required.
- Your computer should contain at least 512K or more of free RAM.
- KWIKSTAT graphics require an EGA or VGA compatible monitor. Many
- printers are supported. A mouse is optional.
-
- INSTALLATION
-
- In most cases, for a quick installation to a hard disk, you enter the
- command:
-
- INSTALL
-
- Follow the instructions on the screen. This procedure will install the
- program to a disk, and will automatically run the KWIKSTAT setup
- program. After installing KWIKSTAT, you can begin the program from the
- DOS prompt by entering the command KS.
-
- See the document on disk named KSWINDOWS.DOC for information on
- installing KWIKSTAT as a Windows icon.
-
- USING THE KWIKSTAT MENUS
-
- KWIKSTAT menus are similar to a windows menu system. The main menu bar
- contains five options: File, Edit, Analyze, Helps and About. Using the
- right and left arrow keys on the cursor pad, you can move the menu
- selection to one of the other menu bar options. Pressing the right
- arrow key once moves the menu bar option from File to Edit. The File
- pull-down menu vanishes and the Edit pull-down menu appears. Pressing
- the left arrow key moves the selection back to the File menu. Or,
- point to a menu option with the mouse and click.
-
- To select options from an extended menu (pulled-down), use the up and
- down arrow keys to highlight the option you desire, then press the
- Enter key. Or, press the first letter of the option name. If you are
- using a mouse, point to the selection with the mouse pointer and
- click. Here is brief description of each menu:
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 2
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
-
- USING THE FILE MENU
-
- Before you can create a graph or calculate statistics, you must
- create a database and enter data. The options are:
-
- NEW DATABASE - You must create a new database and enter data before
- doing any analysis or creating a graph. The program creates and reads
- dBase (.DBF) type file format databases.
-
- OPEN A DATABASE - Open an existing database. A database must be
- opened so the program will know where the data is located.
-
- SUBSET DATABASE - Creates a new database that is a subset of the
- current database.
-
- COPY/BACKUP - Creates a copy of the database.It is useful to create a
- duplicate copy in case the original copy is damaged.
-
- LIST (DISPLAY) THE CONTENTS OF THE DATABASE - Displays the information
- in the database to the screen.
-
- MODIFY OR DISPLAY DATABASE STRUCTURE - Allows you to view or change
- characteristics about the database, including field widths and types.
-
- KILL - Deletes a database file from your disk.
-
- FILE UTILITIES - Imports information, creates reports, or outputs
- data.
-
- EXIT - Ends the program.
-
- USING THE EDIT MENU
-
- The EDIT menu contains options that allow you to enter new data
- into a database, edit data currently in a database, and other
- editing options:
-
- EDIT RECORDS - Change data already in the database.
-
- APPEND RECORDS - Add new records to the database.
-
- MISSING VALUE CODES - Define missing value codes for your database.
- Refer to the section titled "Setting Missing Value Codes".
-
- PACK DATABASE - Permanently erase all records marked for delete.
-
- ZAP - Get rid of all records in a database.
-
-
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 3
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- USING THE ANALYZE MENU
-
- The KWIKSTAT ANALYZE menu allows you to choose which analysis module
- to run. The menu items on the ANALYZE menu are:
-
- Descriptive Statistics
- Graphs - Descriptive & Comparative
- XYZ Visualization/Spin Plot
- t-tests and Analysis of Variance (ANOVA)
- Nonparametric Comparisons
- Regression & Correlation
- Crosstabulations, Frequencies, Chi Square
- Life Tables and Survival Analysis
- Data Generation, Concepts and Simulations
- 2-Way Advanced ANOVA Designs (Professional edition)
- Multiple Comparisons (Professional edition)
- Advanced Regression (Professional edition)
- Time Series Analysis (Professional edition)
- Quality control graphs and charts (Professional edition)
- Pareto Charts (Professional edition)
-
- USING THE HELP MENU
-
- The KWIKSTAT Help system contains items to help you operate the
- program. These include:
-
- PROGRAM HELP - Contains general program help information
- TUTOR - Learn how to use the program
- DECIDE WHAT ANALYSIS TO USE
- CHANGE SETUP OPTIONS - Color, Printer, etc.
- AUTOHELP/Hints (On or Off)
- GO TO DOS, Return with Exit (Shell)
-
- TUTORIAL:TRY THIS EXAMPLE
-
- This short tutorial will give you a feeling for how to use KWIKSTAT.
- It will assume you are using KWIKSTAT on a hard disk. To begin
- KWIKSTAT, you must first be in the \KS4 directory on your hard disk.
- Use the CD (Change Directory) command from the DOS prompt to change to
- the \KS4 directory by using the command:
-
- CD\KS4 (or the directory where you installed KWIKSTAT.)
-
- Once in the \KS4 directory, begin KWIKSTAT with the KS command:
-
- KS
-
- The FILE pull-down menu will appear. (If the ANALYZE pull-down menu
- appears, press the left arrow key twice to open the FILE menu.) This
- example will use data already stored in a dBase ".DBF" file named
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 4
-
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- EXAMPLE. Follow these steps:
-
- Step 1 Select a data file: Open the database named EXAMPLE by
- selecting the Open a database option from the FILE menu, then choose
- EXAMPLE from the list of files. (If the EXAMPLE database does not
- appear on the list of databases, you may not have installed the
- program correctly.) Once the database is opened, a notice at the
- bottom of the screen tells you that the database named EXAMPLE is
- open, and it contains 50 records.
-
- Step 2 View the contents of the database: Choose the List (display)
- option from the menu.
-
- Step 3 Choose the ANALYZE pull-down menu: From the ANALYZE pull-down
- menu, choose the Graphs option. KWIKSTAT now switches to the Graphs
- module (which may take a few seconds). Soon, you will see the Graphs
- module menu.
-
- Step 4 Select a plot type: From the Graphs menu, choose the TIME
- SERIES PLOT option. The program now displays a screen with the fields
- available for use by the graph. The field names appear in a pick box
- to the left of the screen, and an empty box appears to the right of
- the screen.
-
- Step 5 Select fields to plot: From the left screen (list of fields),
- choose which fields to plot in the time series plot. Choose the fields
- TIME1 and TIME2.
-
- When you choose a field, it will appear in the "Fields to Graph" box.
- After you choose the two fields, choose "Finished Choosing Fields."
- After a few seconds, a time series plot will appear containing two
- lines.
-
- The menu above the graph may be used to select user definable features
- of the graphic display. The options include:
-
- EXIT - exit the graph and return to the module menu.
-
- OPTIONS - choose options for the graph including title, axis names,
- footnote, and other options.
-
- PRINT - print the graph to your printer.
-
- CAP/PCX - capture the graph as a PCX file.
-
- GET COLORS - choose colors to be used to display the graph.
-
- +/- Smartpoint(tm) pointer used to select a datapoint on the screen.
- Information about the selected point will be displayed. (see step 7.)
-
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 5
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- Step 6 Control the plot menu: On all graphic screens in KWIKSTAT, a
- similar menu will appear at the top of the screen. If you want the
- menu to temporarily vanish, press the spacebar. Press the spacebar
- again for the menu to reappear. The menu is active even if it is not
- shown.
-
- Step 7 Using SmartPoint(tm): If you are using a mouse, place the mouse
- pointer on a datapoint on the screen and click. Or, if you are not
- using a mouse, press the + (plus) key, then use the cursor keys to
- position the + over a datapoint on the screen, and press Enter.
- Information about the datapoint you selected will be displayed on the
- screen. This feature is particularly helpful in identifying points
- that are interesting or "outliers." Press Enter to return to the plot.
-
- Step 8 Select color options: Press G or click on the "get color"
- option. The color menu will appear. From this menu you can select
- color options. Most plots contain the following "get colors" menu:
-
- Menu - returns to the main graph menu
- graph - changes graph colors
- screen - changes background screen colors
- labels - changes label colors
- default - returns plot to original default colors
- b&w - displays plot in black and white
- help - displays help system
-
- Some "get color" menus also contain the option:
-
- tile - paints the plot using tiles rather than solid colors
-
- Step 9 End this example: Choose Menu to return to the Graph menu.
- Choose Exit to return to the main graph menu. Choose Exit again to
- return to the module menu.
-
- TIP: When you choose to print or capture the screen, the menu will
- vanish, so the menu will not appear on the printout or PCX graphic.
-
- NOTE: You can also go through an on-screen tutorial on how to create a
- chart by choosing the TUTORIAL option on the HELPS pull-down menu.
-
- EXAMPLE 2: DESCRIPTIVE STATISTICS
-
- This example uses the data stored in the database named EXAMPLE.
-
- Step 1 Open the database: To open the EXAMPLE database, select the
- Open a Database option, then choose the EXAMPLE database.
-
- Step 2 Select an analysis module: Open the ANALYZE pull-down menu and
- choose the Descriptive Statistics option from that menu.
- KWIKSTAT switches to the Descriptive Statistics module.
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 6
-
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
-
- Step 3 Choose analysis type: From the Descriptive Statistics menu,
- choose "Detailed statistics (single interval variable)." The program
- now displays the variables available for analysis from the database.
-
- Step 4 Select a field: Select the AGE variable. KWIKSTAT will perform
- calculations on the data in field AGE, and will produce a screen of
- descriptive statistics. At the bottom of this
- screen are several options.
-
- The Descriptive Statistics report screen menu options are:
-
- Exit - return to the main module menu
-
- graph - displays a graphic representation of the data
-
- view/print - allows you to print the information using the KWIKSTAT
- text viewer.
-
- ci - allows you to choose the confidence interval level.
-
- percent - allows you to choose what percentiles will be displayed.
-
- new var - returns you to the variable selection menu.
-
- Step 5 Display the graph: Choose the Graph option. This screen allows
- you to examine the distribution of numbers in the variable being
- analyzed (AGE in this case.) Several options on this menu that were
- not described in the previous example are:
-
- exit - returns to the descriptive statistics summary screen.
-
- mean CI off/on - displays a normal curve on the histogram, and shows
- where the mean and confidence interval is located on the box plot.
-
- print - prints the screen to the printer.
-
- + (plus) and -(minus) - redraws the histogram using more or fewer
- classes. dist. off/on -- allows you to display a cumulative
- distribution for the data.
-
- cap/PCX - captures the graph in a file using the PCX graph format.
-
- b&w or color - displays the graph using black and white or color.
-
- Step 6 End this tutorial: Choose Exit to return to the previous
- screen. Choose Exit again to return to the module menu. End KWIKSTAT
- by choosing the Quit option. This ends the tutorial.
-
-
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 7
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- ===========================
- USING THE KWIKSTAT DATABASE
- ===========================
- The FILE and EDIT pull-down menus are used to manage your data.
-
- Here is a roadmap to help you find the area of this chapter that
- will be most helpful to you according to your database needs:
-
- YOUR DATA IS ALREADY IN A DBASE DATABASE: If your data is already in a
- database, you may not have to use any of the procedures in this
- chapter. Simply copy your database into your KWIKSTAT data
- subdirectory, and it will be accessible immediately. If you have
- missing values, you should review the section titled "Missing Value
- Codes." If you have memo fields in your database, review the section
- called "Using dBASE files."
-
- YOU NEED TO ENTER YOUR DATA: If your data is not already in a file,
- you will need to create a database and enter your data. In this case,
- read the next few sections beginning with "An Overview of Database
- Creation and Design" and perform the two examples to learn how to
- create a KWIKSTAT database. Your data is in a non-dBASE file: If your
- data is already on the computer, but not in a dBASE (.DBF) file, you
- can usually import the data into KWIKSTAT. See the section titled
- "Using data from other programs" later in this chapter.
-
- DATABASE CREATION AND DESIGN
-
- The process for entering data and performing an analysis can be
- summarized in three steps:
-
- Step 1: Create a database.
- Step 2: Enter data into the database.
- Step 3: Choose an analysis option.
-
- OPTIONS FOR CREATING A NEW DATABASE
-
- Before you can enter data into a database, you must create a new
- database. The New Database option on the FILE Menu is used to
- create a new database. The structure, or layout, of a database must
- be described before you enter your data. KWIKSTAT allows you to
- create a new database in two ways:
-
- 1. Choose from a predefined structure or
- 2. Create a customized database structure.
-
- The following sections describe these two options.
-
-
-
-
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- Please Become a Registered User
-
- 8
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- CREATING A DATABASE FROM A PRE-DEFINED STRUCTURE
-
- A pre-defined structure is a "blank" database designed for a
- particular analysis type. Using a pre-defined database allows you to
- create a database for your analysis without having to worry about what
- fields are necessary, what type they should be, their width, and so
- on.
-
- The list below contains examples of some of the pre-defined database
- descriptions available when you choose to create a New Database.
- Choose the option that will create a database structure for the kind
- of analysis you will perform. (You may have to scroll to see some of
- the options.)
-
- CREATE A CUSTOMIZED DATABASE
- SINGLE VARIABLE, DETAILED STAT, HISTOGRAM, STEM & LEAF
- GROUPED HISTOGRAM, STATISTICS OR STEM & LEAF
- SIMPLE BAR CHART: LABEL AND VALUE
- PIE CHART: LABEL AND VALUE
- ETC...
-
- CREATING A CUSTOMIZED DATABASE
-
- If none of the pre-defined database structures meet your needs, you
- need to create a customized database. The following sections describe
- how you create a customized database structure to match your analysis
- needs.
-
- SPECIFYING FIELD TYPES REQUIRED BY AN ANALYSIS
-
- When you create a new database, you must specify certain
- information about each data field, including the field name, type,
- width and number of decimals (if any):
-
- 1. The FIELDNAME: A fieldname must be 1 to 10 characters in length and
- MUST begin with a character (a to z) and can contain letters, numbers
- and the underscore character "_". Upper and lower case DO NOT matter,
- since the name is always translated into all upper case.
-
- 2. The TYPE:Type may be . . .
-
- CHARACTER - May contain any characters.
-
- NUMERIC - Must contain numbers only. Example legal numbers are:1.00,
- -4.32, 6, 10000. Example illegal numbers are: 450-23-1232, $23.95,
- 40%. (For data like these, use the character type.)
-
- DATE or LOGICAL fields can be created in KWIKSTAT, but KWIKSTAT
- analyses will only use numeric and character fields. Thus, date and
- logical fields are treated the same as CHARACTER fields, except for
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- Please Become a Registered User
-
- 9
-
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- subsettings and in transformations (Replace).
-
- 3. The WIDTH of the field: Choose a width so that the maximum number
- of characters needed will fit into the field. For DATE or LOGICAL
- types, field widths are automatically set at 8 or 1 respectively.
-
- 4. DECIMALS:Decimals are only valid for numeric fields. This specifies
- to KWIKSTAT how many decimals to retain in the field. For example, if
- you wish to store numbers that are dollar prices, your data may look
- like "9999.99". This field would have a width of 7, with 2 decimals.
-
- KWIKSTAT DATABASE LIMITATIONS
-
- Maximum of 250 fields.
- Maximum width of a field name is 10 characters.
- Maximum width of a cell is 60 characters (15 for numbers).
- Dates are always 8 characters and logical fields are 1 character wide.
- Memo fields are not supported.
-
- DATABASE EXAMPLES
-
- This section provides you with two examples of creating a KWIKSTAT
- database. Go over these examples before creating your own database and
- performing your own analysis. Following these examples will answer a
- number of questions you may have about how to use KWIKSTAT.
-
- EXAMPLE 1, USING A PRE-DEFINED STRUCTURE
-
- This example shows how you would perform an independent group t-test
- in KWIKSTAT using one of the pre-defined database structures. In this
- example, 13 plants were randomly allocated to two groups. Group one
- received the present fertilizer and group 2 received a newer
- fertilizer. After a period of time, you observed the heights of the
- plants. The results are:
-
- Data for independent group t-test (fertilizer study)
-
- Present Newer Fertilizer
- 46.2 cm 51.3 cm
- 55.6 52.4
- 53.3 54.6
- 44.8 52.2
- 55.4 64.3
- 56.0 55.0
- 48.9
-
- In order to enter this into a database, you must assign group numbers
- (or letters) to each group. For example, we will call the "Present
- Fertilizer" group 1 and the "Newer Fertilizer" group 2.
-
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- Please Become a Registered User
-
- 10
-
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- The database will include thirteen records (one for each plant) and
- two fields (one for the response and one for the group indicator).
- When entered into the database, the data will look like this:
-
- Group Height
- 1 46.2
- 1 55.6
- 1 53.3
- 1 44.8
- 1 55.4
- 1 56.0
- 1 48.9
- 2 51.3
- 2 52.4
- 2 54.6
- 2 52.2
- 2 64.3
- 2 55.0
-
- Step 1 Create the Database: From the FILE Menu on the main KWIKSTAT
- menu screen select New database.
-
- Step 2 Name the Database: You will be prompted to enter the name of
- the database you are creating. Type a name (e.g., TTEST (maximum of 8
- characters)) and press Enter.
-
- Step 3 Select a Structure type. A screen with the instruction "Choose
- the database type to create from the menu below" will appear. Since
- you are performing an independent group t-test, you can select the
- option titled INDEPENDENT GROUP T-TEST OR ANOVA from this list. This
- process automatically builds a database structure suitable for
- entering data for this kind of analysis. In this case, the database
- will contain a grouping field GROUP (where you will enter a 1 or 2,
- the fertilizer type) and an observation field OBS (where you will
- enter the height.)
-
- Step 4 Enter the Data: A data entry screen will appear where you will
- enter the data. In the spreadsheet type of entry, the field names are
- listed at the top of the screen, and the record numbers at the left
- side. The data you will enter in the first record is 1 (press Enter)
- and 46.2 (press Enter). When you type the 46.2 and press Enter, your
- cursor will automatically move to record number 2, where you will
- enter 1 and 55.6, and so on.
-
- Enter the data for the thirteen records. For each record of a "Present
- Fertilizer" observation, enter "1" for the GROUP variable. For the
- "Newer Fertilizer" observations enter a "2" for the GROUP variable.
- The eighth record is 2 and 51.3. Once all 13 records have been
- entered, the program will be waiting for a 14th record to be entered.
-
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- Please Become a Registered User
-
- 11
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- Since there is no 14th record, press the F7 function key (Exit) to end
- the data entry process. KWIKSTAT will return to the Data main menu.
-
- Step 5 Performing the Analysis: From the main KWIKSTAT menu, select
- ANALYZE. From the ANALYZE pull-down menu, select t-tests and Analysis
- of Variance (ANOVA). The menu will appear.
-
- Select Compare independent groups (t-test, ANOVA). A field selection
- dialog box titled "Choose a grouping variable" will appear with the
- following options:
-
- Exit Choices
- GROUP (N)
- OBS (N)
-
- Select GROUP as the grouping field. Another dialog box will appear
- titled "Choose a data (numeric only) variable" with the same options.
- Select OBS, as the data variable (OBS contains the height data). Note:
- If you want to cancel the analysis, you would choose the Exit Choices
- option.
-
- KWIKSTAT will now perform the calculations and display another dialog
- box on the screen with the following options:
-
- A) View or print the calculated results
- B) Graphical Comparison
- Q) Quit, return to main menu
-
- Choose the "A)View..." option. The results of the analysis will appear
- on the screen in the KWIKSTAT viewer. Select Exit (F7) to exit the
- viewer and return to option menu. Choose "Q)Quit..." to return to the
- module menu. Select "X)Exit..." to return to the main KWIKSTAT menu.
-
- EXAMPLE 2, CREATING A CUSTOMIZED DATABASE STRUCTURE
-
- This example shows you how to enter data and perform some simple
- statistics and graphs. It will show you both the spreadsheet and
- database entry screens. The data that will be used is listed below.
- The GRADE variable is the grade received in the class, AGE is age, SEX
- is sex, WT is weight and SCORE is the score on a pre-test (maximum of
- 25 points). In database language, these variables are called fields.
-
- Step 1 Choose the New database option: From the FILE menu, choose the
- New Database option. You will be prompted to enter the name of the
- database. Enter the name MYDATA (a DOS compatible filename).
-
- Step 2 Choose Customize option: Once you have entered a filename for
- the database, a list of database structures will be displayed similar
- to the list on page 2-4. For this example, choose the CREATE A
- CUSTOMIZED DATABASE option.
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- Please Become a Registered User
-
- 12
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
-
- GRADE AGE SEX WT SCORE
- 1 A 18 M 165 22.3
- 2 B 19 M 145 22.8
- 3 B 17 F 122 22.8
- 4 C 18 M 196 18.5
- 5 B 17 M 188 19.5
- 6 B 18 F 140 23.5
- 7 C 19 F 121 22.6
- 8 B 20 F 112 21.0
- 9 C 19 F 122 20.9
- 10 A 18 M 176 22.5
- 11 B 18 M 165 23.3
- 12 A 19 M 135 21.8
- 13 A 18 F 121 24.8
- 14 C 19 M 186 16.5
- 15 B 17 M 148 18.5
-
- Step 3: Define the Database Structure: For each field (each item of
- data) in the database, you must specify the following information:
-
- A name of the field - something to identify it
-
- The type of data - is it numeric or character?
-
- The width of the field - enough to hold the biggest entry
-
- Decimal places - if needed
-
- For the data in this example, you will use the following information:
-
- Field name Type Width Dec
- GRADE C 2
- AGE N 3
- SEX C 2
- WT N 4
- SCORE N 5 1
-
- The GRADE and SEX variables are of type "C" (Character) and the rest
- of the variables are numbers "N". Only the SCORE variable requires a
- decimal value. Enter the information about the database structure into
- the database definition screen.
-
- Step 4 Enter the data: A data entry screen will appear listing the
- names of all of the fields and an area to enter the data. KWIKSTAT
- includes two types of data entry screens, database type and
- spreadsheet type. In the Setup routine, you chose one of these two
- entry options. The following discussion shows you how to enter data in
- the spreadsheet screen.
-
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 13
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- TIP: You can toggle between spreadsheet entry mode and database entry
- mode by pressing the F8 (Switch) key.
-
- Step 4A Using a spreadsheet entry screen: The spreadsheet screen, as
- shown in figure 2.7 looks similar to a spreadsheet. If you prefer to
- use the database entry mode, skip to the section titled "Using a
- database entry screen."
-
- The names of the database fields (Grade, Age, etc.) are listed at the
- top of the screen (columns) and the record numbers are listed down the
- left side of the screen (rows). Initially, since you do not have any
- records entered into the database, the only row displayed is the -ADD-
- row, which indicates that you are adding a new record.
-
- To enter data into the database, begin typing the entry for the first
- field (GRADE). Type an A (upper case), then press Enter. Your cursor
- moves to the next field (AGE). Type 18 and press Enter. Type upper
- case M and press Enter. Continue until you have entered 22.3 in the
- SCORE field. When you press Enter after entering 22.3, a new row
- appears to allow you to enter the second record of information, and
- your cursor moves to the first field of this record. Continue entering
- information in the spreadsheet until all records are entered. If you
- make a mistake on a record, you can use the right or left arrow keys
- to move your cursor and correct the mistake. If you discover that you
- have made an error in a previous record skip to step 5 now. When you
- have finished entering the information in the database, end the entry
- procedure, press F7 (Exit.).
-
- Step 5 Correcting errors in the database: Before exiting the data
- entry screen, you can correct errors in data entry mode by using the
- F2 key to toggle into Edit mode. The edit screen is similar to the
- screen used to enter data. Use the cursor keys to move to the field to
- edit, and change the value. Exit the edit screen/data editor by
- selecting the F7 (Exit) command. You will return to the KWIKSTAT main
- menu.
-
- Step 6 Perform a Descriptive Statistics analysis: Once you have
- entered your data into the database, you are ready to perform one or
- more analyses. From the main KWIKSTAT menu, choose the ANALYZE
- pull-down menu. Choose the Descriptive Statistics option on the
- ANALYZE menu. After a few seconds, the Descriptive Statistics menu
- will appear. This menu lists the options you can choose from the
- Descriptive Statistics module.
-
- Step 7 Select Detailed Statistics: To calculate detailed statistics
- for a variable in your database, select the option called "Detailed
- Statistics (single interval variable)". A screen will appear prompting
- you to specify what field to use in the calculations. Select AGE. The
- detailed statistics screen for the selected variables will appear on
- the screen. Once you have examined these results, select Exit to exit
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 14
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- the screen. This output is discussed later in "Using Descriptive
- Statistics."
-
- USING THE KWIKSTAT FILE MENU
-
- The FILE Menu is the first menu you normally use when you begin
- KWIKSTAT. From this menu, you open a database or create a new
- database. Either way, you usually must have data in a database before
- you can perform an analysis. This section describes the options on the
- FILE Menu.
-
- NEW DATABASE
-
- When you choose New Database from the FILE Menu, you will be prompted
- to enter the name of the database. Enter a file name such as MYDATA.
- (Eight characters maximum.) Once you have entered a filename for the
- database, you can choose from a list of pre-defined database
- structures, or create your own. See Examples 1 and 2 later in this
- chapter for a tutorial on using a pre-defined structure or creating a
- customized database structure.
-
- OPEN A DATABASE
-
- The Open a database to use option on the FILE Menu allows you to
- access information in a dBASE file that you created in KWIKSTAT, in
- dBASE, or in any other program that creates .DBF files.
-
- If the database you want to use is not in the current (default)
- directory, you can temporarily change the default directory by
- selecting "Choose New Path (F2)". You will be asked to enter a path
- name (such as \DB3). Then, the .DBF files in that directory will be
- displayed in a list, and you can choose the database to use from that
- list. Another way to open a database that is not in the default
- directory is to enter it by name. To do this select "Enter Choice by
- Name (F3)". You will be prompted to enter the name of the database to
- use. For example, if the database you want to use is MYDATA.DBF and it
- is in the \DB3 directory, you would enter \DB3\MYDATA. Do not include
- the .DBF extension in the name.
-
- Once a database is open, you will see its name at the bottom left of
- the screen, along with the number of records in the database. Once a
- database is open, you can edit, pack, modify, set missing values,
- subset and list the database using the other options on the FILE Menu.
-
- SUBSET A DATABASE
-
- The Subset database option on the FILE Menu allows you to create a new
- database from an old one. The new database can be a subset of the old
- one, using a conditional criteria for outputting information from the
- old database to the new one.
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 15
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
-
- For example, suppose you have a database with a field GROUP with
- values 1, 2, 3, 4 and 5. You want to create a database that does NOT
- include Group 5. After choosing Subset database from the FILE Menu,
- you are asked for the name of the new database. For example, your new
- database might be named NO5.DBF. You are asked for the field name to
- be used in the selection criteria. In this case, you would choose the
- field named GROUP. Next you must enter the selection relationship. It
- will be described as a numerical expression. The conditional operators
- you may use are:
-
- = (equal)
- > (greater than)
- < (less than)
- >= (greater than or equal to)
- <= (less than or equal to)
- <> (not equal to)
-
- For example, you would enter the condition
-
- GROUP <5
-
- You can also use the logical operators .NOT., .AND., and .OR.. It is
- important that a dot (.) appear before and after each logical
- operator. For example, a conditional expression to include only groups
- 1 and 5 would be
-
- GROUP = 5 .OR. GROUP = 1
-
- Other examples of conditional expressions are
-
- GROUP > STATUS
- GROUP < WEIGHT*HEIGHT
- TIME1 = TIME2*1.96
- SEX <> 'F'
- TIME1 <=20 .AND. SEX = 'M'
-
- When you choose the Subset option from the FILE Menu, a Subset dialog
- box appears on the screen. There are two items you must enter in the
- Subset dialog box. First is a name for the new database. This must not
- be the same name as the current database. Then, you must enter the
- subset criteria. Examples of subsetting criteria are:
-
- Once you have entered the filename and condition, press the F7 key to
- begin the subset procedure. A database with the name you specified
- will be created, containing the records selected by your condition
- statement. Note: When creating conditional expressions for subsetting,
- use the functions described in the table "Database Calculator
- Functions" later.
-
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 16
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- COPY/BACKUP DATABASE FILE
-
- The Copy/Backup Database File option on the FILE menu allows you to
- quickly create a backup copy of your database information. This is
- recommended, particularly for large database because sometimes
- databases become corrupt or are made unusable for some other reason.
-
- LIST RECORDS
-
- The List (display) the contents of a database option on the FILE Menu
- allows you to look at the information in your database.
-
- MODIFY OR DISPLAY STRUCTURE
-
- The Modify or Display database structure option on the FILE Menu
- allows you to display the structure of your database, and allows you
- to change characteristics about the database structure. When you
- choose to display the structure, a list of all field names, their
- types, widths and decimals (if any) are listed. When you choose to
- modify a database, you are given a chance to modify the
- characteristics of each field. Your options are:
-
- Delete the Field
- Change Name of Field
- Change Type of Field
- Change Width of Field
- Change Number of Decimal Places
-
- If you change the type of field, say from character to numeric, the
- program will attempt to convert the contents of the field to its new
- type. When you modify a database, you will be asked to enter the name
- of a new database. This means that the modified database will be in a
- new file, and your old original database will remain intact. If you no
- longer want the old database, you must delete it by choosing the Kill
- database file option from the FILE Menu.
-
- KILL (DELETE) A DATABASE
-
- The Kill - Delete database file option allows you to delete a database
- and its related missing values files (if any.)
-
- FILE UTILITIES - EXPORT, IMPORT, REPORT
-
- This menu provides several data utilities. When you choose this
- option, the KWIKSTAT utilities menu appears. It allows you to choose
- from these options:
-
- Export data to an SDF file -- This option allows you to write out the
- data in a database to an ASCII file. This option is useful when you
- are wanting to transfer data from your KWIKSTAT database to another
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 17
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- program that does not read .DBF files. See "Exporting Data" later in
- this chapter.
-
- Import data from a Comma Delimited file or from a 1-2-3 file -- See
- the section below titled "Entering or Importing Data" for information
- on how to import data into a KWIKSTAT database.
-
- Report - Allows you to produce a report using the data in your
- database. See the section titled "Printing a Report" later in this
- chapter
-
- Sort - (Professional Edition Only) Allows you to sort your database in
- ascending or descending order using any field in the database.
-
- EXIT KWIKSTAT
-
- Use this option to end the KWIKSTAT program.
-
- USING THE KWIKSTAT EDIT MENU
-
- The EDIT menu allows you to modify and manage data in a KWIKSTAT
- database. Often, after you have created a database, you need to add
- new data or modify the current data. You can also add new fields,
- calculate new variables and delete fields or records. This section
- describes the options you can access from the EDIT menu.
-
- EDIT RECORDS, ADD, DELETE OR REPLACE FIELDS
-
- When you choose the Edit records option, the KWIKSTAT data editor will
- appear. The data editor is described in detail in the section titled
- "Using the KWIKSTAT Data Entry Screens" later in this chapter.
-
- APPEND RECORDS, FROM KEYBOARD OR FILE...
-
- The Append records option allows you to add new records to an existing
- database. You have three data entry options:
-
- Enter data from keyboard - Allows you to enter data by typing it on
- the keyboard.
-
- Enter data from a text file - Allows you to import data from an ASCII
- file. See the Section titled "Entering and Importing Data" later in
- this chapter.
-
- Append data from a dBASE file - Allows you to append data from another
- in this chapter.
-
-
-
-
- --------------------------------------------------------------------
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-
- 18
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- MISSING VALUES CODES
-
- Sometimes in the collection of data there are values that are lost or
- cannot be gathered. These are called "missing values". When such
- values occur, it is important for the program to know that the values
- are missing so that statistical calculations may take this into
- account. Missing values are usually designated as an impossible value.
- For example, the missing values designated for the variable AGE may be
- -9, since it is impossible for the variable AGE to have the value -9.
- When the program is asked to calculate the mean of age, for example,
- it will ignore those records where AGE is -9 in that calculation if -9
- has been specified as the missing value code. In most KWIKSTAT
- procedures, there is a casewise deletion of the record from
- calculation whenever a missing value is encountered.
-
- Once you designate a missing value code for a variable, it is up to
- you to make sure that this code gets placed into your database in the
- proper records and fields. For example, if you have designated -9 as
- the missing value code for AGE, you must make sure that in your
- database a -9 appears in the field AGE if that data is missing or
- unknown.
-
- The Indicate missing value codes option on the FILE Menu is used to
- set up these values. When this option is selected, the program will
- display an entry screen that is similar to a data entry screen. You
- may enter one missing value for each field name. The missing value
- must obey the definition of the field in terms of length and type.
-
- Once missing values are entered, they are stored on disk in a file
- named filename. MV, where "filename" is the name of the designated
- database. If a new variable is created using the transformation
- procedure, its missing value is appended to the missing value file.
-
- You may change or correct the missing values for a database at any
- time by calling up this option. If missing values are already
- designated for the database, they will be displayed on the entry
- screen, and you may edit them or accept them as they are.
-
- Note: If missing values are NOT used, and there is a blank numeric
- variable in a calculation, it may be treated like the value 0 (zero),
- so it is important to use missing values if your data contains such
- entries. Otherwise, the statistical calculations may be in error!!
-
- PACK DATABASE
-
- The records marked for delete are not actually erased from the file at
- this point. However, they will be ignored in most analyses, and will
- continue to be displayed when you edit the database. See "Edit Mode
- Options" later.
-
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 19
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- If you want to permanently get rid of the records you have marked for
- delete, choose the Pack procedure from the FILE Menu. This procedure
- erases all "deleted" records from the database.
-
- ZAP - GET RID OF ALL RECORDS
-
- The Zap option in the EDIT menu allows you to quickly erase all
- records from a database. To use this option, open a database, then
- choose Zap.
-
- USING THE KWIKSTAT DATA ENTRY SCREENS
-
- If there is a need to change data already in a database, you may
- choose the Edit records option from the EDIT menu. Editing is similar
- to entering data. Use the up and down arrow keys to move from field to
- field within a record and type in any change you want to make in the
- field. The section below describes the menu bar options available to
- you in the data entry screen.
-
- USING APPEND & ENTRY SCREEN MENU BAR OPTIONS
-
- When you are appending information to the database, there are several
- function key options that you can choose. These options are listed at
- the bottom of the entry screen.
-
- APPEND MODE OPTIONS
- To choose an option, press the function key related to the option, or
- point to the option with the mouse and click. The options available
- are:
-
- F1 Help - Displays the KWIKSTAT Help menu.
-
- F2 Edit - Toggles between edit mode (correct current entries) and
- append mode (add new entries).
-
- F7 Exit- Exits entry mode and returns you to the main KWIKSTAT menu.
-
- F8 Switch - Switches between spreadsheet type entry and database entry
- mode.
-
- F10 Print - Print the current record to the printer or to a file.
-
- EDIT MODE OPTIONS
-
- When you are in edit mode, a slightly different menu bar appears
- containing the following items:
-
- F1 Help - Displays the KWIKSTAT Help menu.
-
- F2 Append - Toggles between edit mode and append mode.
- --------------------------------------------------------------------
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-
- 20
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
-
- F3 Delete - Marks one or more records for deletion. When you choose
- this option you will be able to choose from the following options:
-
- A) Mark this record for delete
- B) UNMark all records where fieldname = value
- C) Mark all records for delete where fieldname = value
- D) UNMark a range of records
- E) Mark a range of records
- Q) Quit this option
-
- You can mark as many records as you choose. Once you have marked the
- records for delete, you can pack the database using the Pack option in
- the Edit pull-down menu.
-
- ANALYSIS TIP: Marking records for delete is a quick and simple way to
- do an analysis on a portion of your database. Mark the records you
- want to eliminate from an analysis, then perform the analysis.
- KWIKSTAT will ignore the deleted records. Later, you can undelete the
- records.
-
- Note: A ^U (Ctrl-U) also deletes and single undeletes records. Place
- your cursor on the record to delete or undelete, and press ^U.
-
- F4- Erase/Insert - the current record permanently from the database.
- (Only in spreadsheet entry mode.) When you choose this option the
- following menu items will appear:
-
- A) Erase records beginning with record #
- B) Insert blank records before record #
- Q) Quit this option
-
- To erase one or more records, display the record in Edit mode.
- Highlight the record to erase, and press the function key F4. You can
- then choose to erase the single record or a range of records.
-
- F5 Goto - Go to a record number.
-
- F6 Undo - Returns last record changed to its previous values.
-
- F7 Exit - Exits entry mode and returns you to the main KWIKSTAT menu.
-
- F8 Switch - Switches between spreadsheet type entry and database entry
- mode.
-
- F9 Field - Insert or Delete a field in the database or Replace the
- contents of a field. See "Creating New Fields and Replacing the
- Contents of a Field" below.
-
- F10 Print - Prints the contents of the current record to a printer or
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 21
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- file.
-
- CREATING NEW FIELDS AND REPLACING THE CONTENTS OF A FIELD
-
- Using the F9 Field option in the Spreadsheet data entry screen, you
- can create new blank fields of any field type, and place information
- in those fields that is either a numeric or character expression. The
- option menu displayed when you choose F9 Field is:
-
- A) Insert a new field after the field: fieldname
- B) Delete the field named: fieldname
- C) Replace contents of field: fieldname
- D) Set missing values for fields
- Q) Quit this option
-
- The following sections "Creating a New Field" and "Replacing the
- Contents of a Field" describe these procedures.
-
- CREATING A NEW FIELD
-
- You may create a new field in a database within an edit screen by
- choosing the F9 (FIELD Insert) option. After creating a new field, you
- can then use the F9 (FIELD Replace) option to place a value in the new
- field.
-
- When you choose the Field/Insert option in the edit screen (F9), you
- will be prompted to enter information about the new field.
-
- Define a name for the new field
- Define the field type
- Define a width for the new field
-
- For numeric variables,
- Define the number of decimals, if any
- Define a missing value code. If none is selected, it is assumed to
- be 0 (zero).
-
- After entering a new name for the field, you will be prompted to enter
- the field type, width and decimals (if numeric). For example, if your
- new field is numeric with a width of 8, and 2 decimal places, you will
- enter
-
- N,8,2
-
- If the field is Character with a width of 3, you would enter
-
- C,3
-
- After you enter the type and width information, you will be asked if
- you want to enter missing value codes.
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 22
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
-
- Note: All of the normal restrictions of defining a field remain.
-
- TIP: To create a new field containing a new value that is a numeric
- transformation of other fields, first insert the new field using the
- F9 Field/Insert option, then use the F9 Field /Replace option to place
- the value in the new field.
-
- REPLACING THE CONTENTS OF A FIELD (TRANSFORMATIONS)
-
- You can use the F9-Field Replace option in the Edit screen to replace
- the existing contents of a field, or place new information in a newly
- created blank field. KWIKSTAT provides a number of numeric and
- character functions to enable you to do this.
-
- For example, if you wanted to replace the contents of the field NEW
- with the values TIME1/AGE:
-
- Step 1 Highlight the field to replace: In the edit mode, highlight the
- field whose contents you want to replace. Press the F9 (Field) option,
- and choose "Replace the Contents of a Field" option from the Field
- menu. A dialog box will appear.
-
- Step 2 Specify which records to replace: The default is ALL, which
- means all records in the database. Or, enter a range such as 1-20,
- which would mean only perform the replacement in records numbered 1
- through 20. Then, press Enter.
-
- Step 3 Specify what to place in the field: For example, enter the
- formula TIME1/AGE in the Replace With entry field, where TIME1 and AGE
- are two other fields in the same database.
-
- Step 4 Specify a condition for replacing (if any): The default is
- NONE. For example, if you only want the replacement to be for records
- whose value of AGE is greater than 20, you would enter the expression
- AGE>20 in the condition entry field.
-
- Step 5 Begin the replacement: Press F7 when you have finished entering
- the Replace information, and the replace will begin. When it is
- finished, you will return to the edit screen.
-
- USING DATABASE AND MATHEMATICAL EXPRESSIONS
-
- The kinds of expressions you can use in Subset and Replace options are
- described below. KWIKSTAT supports two kinds of expressions.
-
- 1. Database expressions (most normally used.)
-
- 2. Mathematical expressions (signaled with an = preceding the
- expression.)
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 23
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
-
- USING DATABASE EXPRESSIONS
-
- Database expressions allow the use of common character, numeric, date
- and logical fields in the expression. Use the mathematical expression
- only when you must use mathematical functions not in the normal
- database expression list. Here are the usage criteria:
-
- In a REPLACE WITH field: Use either a database expression or a math
- expression.
-
- In a CONDITION field: Use only a database expression.
-
- Most expressions can be handled with the database expressions. If you
- find that you cannot create an expression using the database
- functions, go to the section titled "Using Mathematical Expressions"
- later in this chapter. The following information on how to use
- expressions is useful for both the database and mathematical
- expression types:
-
- Arithmetic operators:
- Add +
- Subtract -
- Divide /
- Multiply *
- Exponentiation ^ (Mathematical expressions only)
-
- For Character fields, the database calculator supports the
- operation:
- Add + (appends one string to another)
-
- Following are a few examples of correct expressions:
-
- AGE/HEIGHT
- LTRIM(FIRST)+' '+LAST
- (AGE*TIME1)+3.2
-
- Note: Literal strings included in expressions must be surrounded by
- single quotes. For example, 'Hello' is a literal string. Character
- field names are used without quotes. For example, NAME is a field
- name. A correct string expression using these two strings would be:
-
- 'Hello '+NAME
-
- DATABASE CALCULATOR FUNCTIONS SUPPORTED
-
- The following functions may be used in expressions both in the
- "Replace With" and "Condition" fields. In this table the arguments
- have the following meanings
-
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 24
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- NUM - Numeric argument
- STG - String (Character) argument
- DATEFMT - Date argument, MM/DD/YY
- LOGICAL - T or F
- LEXP - Logical Expression
- AEXP - Any Expression
- | means OR, choose one or the other option.
- [ ] means optional argument
-
- Database Calculator Functions
-
- Name Meaning Example of use Type
- ------- ------------------------------------------------
- ABS Absolute value ABS(NUM) N
- ASC Ascii value ASC(STG) N
- AT AT Find AT(STG1,STG2) N
- CALENDAR Number to Date CALENDAR(NUM) D
- CAPS First Letter Cap CAPS(STG) C
- CHR Number to String CHR(NUM) C
- DATE System Date DATE() D
- DELETED Is record Deleted DELETED() L
- IIF Logical If IIF(LEXP,AEXP1,AEXP2) CNL
- INT Integer Round INT(NUM) N
- JULIAN Date to Number JULIAN(DATE) N
- LEFT Left string LEFT(STG,NUM) C
- LEN String Length LEN(STG) N
- LOWER Lower Case LOWER(STG) C
- LTRIM Trim Left LTRIM(STG) C
- MAX Max of 2 Nums MAX(NUM1,NUM2) N
- MIN Mini of 2 Numbers MIN(NUM1,NUM2) N
- REPLICATE Repeat String REPLICATE(STG,NUM) C
- RIGHT Right String RIGHT(STG,NUM) C
- RTRIM Trim Right RTRIM(STG) C
- SPACE Space SPACE(NUM) C
- STR Number to String STR(NUM) C
- STRING Create String STRING(NUM,NUM|STR) C
- RIGHT Right String RIGHT(STG,NUM) C
- STUFF Stuff String STUFF(STG,NUM,NUM,STG2)C
- SUBSTR Extract String SUBSTR(STG,NUM,[NUM]) C
- TIME System Time TIME() C
- TRIM Trim blanks TRIM(STG) C
- UPPER Upper Case UPPER(STG) C
- VAL String to Number VAL(STG) N
-
- The following functions are supported only in the "Replace With" entry
- field, and only for numeric field types. You MUST precede expressions
- using these functions with an = sign.
-
- An example of the RECODE function, which appears on the following
- table is:
- --------------------------------------------------------------------
- Please Become a Registered User
-
- 25
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
-
- =RECODE(SCORE,1,AGE,10,15)
-
- The five arguments in the RECODE function are:
-
- No. Example Meaning
- 1 SCORE Field to use in compare
- 2 1 Value to assign if comparison is true
- 3 AGE Value to assign if comparison is false
- 4 10 Low range of field to compare
- 5 15 High range of field to compare
-
- Thus, this example means that the value of the RECODE is 1 if SCORE is
- between 10 and 15, else the value is the current value of the AGE
- field for that record.
-
- USING MATHEMATICAL EXPRESSIONS
-
- In the REPLACE WITH field, the default expression type is the database
- type. In order for an expression to be evaluated as a strictly math
- expression, you must place an equal sign "=" at the beginning of the
- expression.
-
- The major difference between the database and mathematical expression
- types are their capabilities. The database expression can handle most
- common calculations, including simple math, string evaluation, and
- date evaluation. The math expression can be used only for strictly
- numeric calculations using one or more of the functions listed in the
- table below, or that uses the exponentiation operator.
-
- For example, if you want to perform the calculation WEIGHT/HEIGHT, you
- can enter the expression as-is in the REPLACE WITH field. However, if
- you want to calculate the log of WEIGHT/HEIGHT, you must enter the
- expression as
-
- =LOG(WEIGHT/HEIGHT)
-
- since the LOG function is not supported as a database expression
- function. The equal sign signals to the program to use the math
- calculator. For example, if you want to create a field that contains
- the record number, you would use the expression
-
- =RECNO
-
- To create a field containing a random number from 0 to 100, you would
- use the expression
-
- =RAND*100
-
-
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- Math Calculator Functions
-
- Name Meaning Example of use
- -------- ----------------------------------
- ABS Absolute value ABS(SCORE)
- AVE Average (Mean) AVE(LIST))
- ACOS Arc Cosine ACOS(SCORE)
- ASIN Arc Sine ASIN(SCORE)
- ATAN Arc Tangent ATAN(SCORE)
- ATAN2 Arc Tangent y/x ATAN2(y,x)
- CSC Cosecant CSC(SCORE)
- COS Cosine COS(SCORE)
- COT Cotangent COT(SCORE)
- EXP Exponentiation EXP(SCORE)
- INT Integer INT(SCORE)
- LN Natural Log LN(SCORE)
- LOG Log base 10 LOG(SCORE)
- MAX Maximum of list MAX(1,T2,3)
- MIN Minimum of list MIN(1,T2,T3)
- MOD MOD of number MOD(9,2) is 9 mod 2
- PI PI PI = 3.14159265358979
- RAND Random number number between 0 and 1
- RECNO Record number database record number
- RECODE Recode number RECODE(SCORE,1,0,1.1,2,2)
- ROUND Rounds a number ROUND(1.236,2)=1.24
- SD Standard Deviation SD(LIST)
- SEC Secant SEC(SCORE)
- SIN Sine SIN(SCORE)
- SQRT Square root SQRT(SCORE)
- SUM Sum of list SUM(1,2,3) = 6
- TAN Tangent TAN(SCORE)
-
- ENTERING & IMPORTING DATA INTO KWIKSTAT
-
- When you choose the Append records... option from the FILE Menu, you
- will be asked to specify entry from the keyboard or from a file (ASCII
- file). For most small data sets, you will probably enter data from the
- keyboard. If your data is already in another program that supports
- ASCII, dBASE and 1-2-3 type files, you may be able to import the data
- from that program into KWIKSTAT. The following information describes
- how to enter data from the keyboard, from an ASCII file or from other
- programs.
-
- Once you have opened or created a database, you can enter data from
- the keyboard by choosing the Append Records/from keyboard option from
- the EDIT pull-down menu. When you choose this option, a sub-menu will
- appear allowing you to choose to enter data from the keyboard, from an
- ASCII file or from a DBF file.
-
-
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- APPENDING DATA FROM ANOTHER DBASE FILE
-
- If you have a dBASE file containing data that you want to append to a
- current dBASE file, use the following procedure.
-
- Note: For this procedure to work, the names of the fields in the two
- databases must be the same. Only fields with the same name will be
- imported.
-
- Step 1 Open a database: Open a dBASE file by choosing the Open a
- Database option on the FILE Menu.
-
- Step 2 Choose Data Entry: From the EDIT menu, choose the Append Data,
- from dBASE option.
-
- Step 3 Specify the name of the dBASE file to read from: Enter the name
- of the dBASE file containing the records you want to append. KWIKSTAT
- will read the data, and will append data from the new database based
- on the fieldnames in the currently opened database.
-
- Step 4 Verify the import: After appending, you should perform a list
- to verify that the database contains the information you want.
-
- USING LOTUS 1-2-3 TYPE FILES
-
- If you have a Lotus 1-2-3 WKS or WK1 file and cannot use the Lotus
- program to translate it, you can use the KWIKSTAT import feature from
- the File Utilities/Import option from the FILE Menu.
-
- Note: Import will allow you to import a maximum of 128 fields.
-
- USING COMMA DELIMITED ASCII FILES
-
- If your program outputs comma delimited ASCII files, that is, there is
- a comma between each field, KWIKSTAT can import this data using the
- "Comma Delimited" option in the File Utilities FILE Menu option.
-
- The data to be imported can contain numbers and character fields.
- Character fields must be enclosed in quotes "". An example file on
- disk is EXCOMMA.DAT. The first few lines of this file are:
-
- "A",12,22.3,25.3,28.2,30.6,5,"Text"
- "A",11,22.8,27.5,33.3,35.8,5,"Text"
- "B",12,22.8,30.0,32.8,31.0,4,"Text"
- "A",12,18.5,26.0,29.0,27.9,5,"Text"
-
- The import procedure looks at the first line of the file to determine
- how many fields to create. This file has 8 fields. The first and last
- are character. The fields will be named VAR1, VAR2, etc. You can
- change these names in the "modify database" option, main menu. The
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- import will attempt to create widths that will allow full storage of
- numbers and text. Everything after that is automated. Look at the
- file with the List option to verify that the imported data is correct.
-
- EXPORTING DATA
-
- You may output the data from your KWIKSTAT (DBF) file into a standard
- ASCII TEXT file. (Often called an SDF file - Standard Data Format
- file.) Outputting the data is useful for transferring your data to
- other programs. Along with the output of data, you may also output a
- "format" file, which describes the contents of the text file. This
- file can be output in "dBASE" style or "SAS" (Statistical Analysis
- System) style. The SAS format could be used in a SAS INPUT statement
- to read the ASCII data file into the SAS program.
-
- To export data, choose the File Utilities option from the DATA
- pull-down menu to display the KWIKSTAT. From the Utilities menu,
- choose the "Output data to an ASCII file (SDF Standard Data Format)"
- option.
-
- PRINTING A REPORT
-
- You may output a listing of the data in the dataset (or a selected
- subset of the database) by using the report facility. To use this
- procedure, choose the "Report: Output data in a report format" option
- after choosing the File Utilities option on the FILE Menu. In this
- procedure you may specify the following report features:
-
- Which Data Fields To Output
- Output Record Number As A Column
- Title
- Number Of Lines Per Page
- Width Of Page (default is 80)
- Output To A File Or Printer
- Output A Subset Of The Data (search)
-
- NOTE:You may want to place a coded variable in your data set which
- will allow you to easily select a subset of data to output. Subset
- searches can be:
-
- 1) Exact: case is ignored.
-
- 2) First one or more letters in a field: (AL* matches ALLEN, ALBERT,
- etc)
-
- 3) Keyword: match a letter pattern within a field (i.e., [AL] matches
- ALLEN, BALES, etc).
-
- The REPORT procedure is menu driven. Simply answer the questions as
- you are prompted. If the report is too wide to fit on a single width
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- of the specified paper width, the report will be printed in parts.
-
-
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- =====================================
- BASIC STATISTICAL ANALYSIS PROCEDURES
- =====================================
-
- This section of the KWIKSTAT manual describes the statistical analysis
- procedures available in the BASIC KWIKSTAT edition. The data
- generation and simulations module contains several examples of
- statistical concepts such as a coin flip, sampling from a
- distribution, and confidence intervals.
-
- USING DESCRIPTIVE STATISTICS
-
- The Descriptive Statistics module allows you to examine summary
- statistics of the data in a database.
-
- DETAILED STATISTICS FROM AN EXISTING DATABASE
-
- This option calculates the mean, standard deviation, median, standard
- error of the mean, minimum, maximum, sum, variance and other
- descriptive statistics for a single variable (field) from a set of
- data.
-
- If your data is already in a database, perform the analysis using the
- following steps. For example, suppose you want to calculate statistics
- for the TIME1 field in the EXAMPLE database.
-
- Step 1 Open the database: Choose Open Database from the FILE pull-down
- menu. Select the EXAMPLE database.
-
- Step 2 Choose Analysis option: Choose the Descriptive Statistics
- option from the ANALYZE menu.
-
- Step 3 Choose the analysis type: Choose the "Detailed Statistics"
- option from the Descriptive Statistics menu.
-
- Step 4 Choose the field to analyze: Choose the TIME1 field.
-
- A screen will appear displaying statistics on that variable.
-
- DEFINITIONS
-
- C. I. - Confidence interval - This is a range that describes (with
- some confidence -- usually 95% confidence) where the actual mean of
- the data probably lies. That is, the true mean of the data shown
- above is somewhere between 20.79 and 21.23, with 95% confidence.
-
- MAXIMUM - The largest number.
-
- MEAN - A measure of central tendency. The arithmetic average. For
- example if you average the three grades 82, 100 and 88 (82+100+88)/3 =
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- 90 -- the average (or mean) is 90.
-
- MEDIAN - A measure of central tendency. The mean is a statistic such
- that 50% of all numbers in the sample are above the mean and 50% are
- below the mean. For example, in the list 1, 2, 3, 4, 5 the median
- would be 3.
-
- MINIMUM - The smallest number.
-
- MISSING - Reports how many numbers had a missing value code.
-
- N - How many numbers were used to calculate the statistics.
-
- PERCENTILES - Tells you what percent of numbers are lower than the
- percentile. For example, the 50th percentile is the median.
-
- S.E.M. - The Standard Error of the Mean measures the spread of the
- data around the mean value.
-
- ST. DEV. - Standard Deviation - measure of the spread of the data. It
- is calculated two ways, using n-1 as a divisor and using n as a
- divisor. Usually, most people use the n-1 version.
-
- SUM - The total of all the numbers added together
-
- TEST FOR NORMALITY - (Professional edition) - This is a test that the
- data is normally distributed. The test statistic is D. If the p-value
- is < 0.05, there is evidence to assume that the data are NOT normal.
-
- TUKEY 5 NUMBER SUMMARY - Essentially, the 0th, 25th, 50th 70th and
- 100th percentile. See the Hoaglin, et al. reference.
-
- VARIANCE - A measure of the spread of the data.
-
- SUMMARY STATISTICS ON A NUMBER OF VARIABLES
-
- This option allows you to calculate statistics on several variables
- (sample size, mean, standard deviation, minimum, maximum, and standard
- error of the mean). If you have a grouping variable in your database,
- you may request output of summary statistics by group.
-
- Suppose you want to know the means of all the quantitative variables
- (AGE, TIME1, TIME2, TIME3, TIME4, STATUS) within each of the three
- groups (A, B, C) in the EXAMPLE database. Follow these steps:
-
- Step 1 Open the database: Choose Open Database from the FILE pull-down
- menu. Select the EXAMPLE database.
-
- Step 2 Choose Analysis option: Choose the Descriptive Statistics
- option from the ANALYZE menu.
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
-
- Step 3 Choose the analysis type: Choose the "Summary Statistics"
- option from the Descriptive Statistics menu.
-
- Step 4 Choose the fields to analysis: Select the fields AGE, TIME1,
- TIME2, TIME3, TIME4, then select the "Finish choosing fields" option.
-
- Step 5 Choose the grouping field: Select STATUS as the grouping field.
- The KWIKSTAT viewer will appear displaying statistics on that
- variable.
-
- Step 6 Exit the viewer: Then exit the module or perform another
- analysis.
-
- DETAILED STATISTICS FROM DATA ENTERED BY COUNTS
-
- If you have a small amount of data or if your data is grouped so that
- you know how many of each number you have (i.e., you have 12 people
- 13 years old, 5 people 14 yrs old, 6 people 15 yrs old, etc.) you can
- enter the data at the keyboard. When you choose this option a screen
- will appear allowing you to enter your data. Either enter a single
- value or a value followed by a comma and the number of times that
- number should be used. For example, entering 34,5 would mean that you
- are entering 5 values of 34. When you enter nothing on a line, this
- signals that you are finished entering the data. A detailed statistics
- screen will appear similar to the one described above.
-
- APPROXIMATE P-VALUE DETERMINATION
-
- This option calculates p-values for four test statistics: normal (z),
- student's t, F, chi-square. Enter the statistic, degrees of freedom
- and the calculated value of the statistic, and the program will tell
- you the p-value associated with that statistic.
-
- To calculate a p-value, follow these steps:
-
- Step 1 Begin the Descriptive Statistics module: From the main menu
- bar, open the ANALYZE pull-down menu, then choose the Descriptive
- Statistics option.
-
- Step 2 Choose the p-value option: Select Approximate p-value
- determination.
-
- Step 3 Enter the p-value information: You will be prompted to enter an
- equation. On the left hand side, designate the test statistic being
- used, i.e., z= , t(df)= , F(dfn,dfd)= , or X(df)=. In parentheses, as
- shown by (df), enter the appropriate degrees of freedom. On the right
- hand side of this equation, enter the calculated value of the
- statistic you wish to know the p-value. For example:
-
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- t(20)=2
-
- means you want the two-sided p-value for a calculated t-statistic of
- 2.00 with 20 degrees of freedom. In this case, the result is p=0.059.
-
- Step 4 Exit p-values: To exit the p-value determination procedure,
- enter End.
-
- STEM AND LEAF DISPLAY
-
- The Stem and Lead Display is a graph created from a series of numbers.
- The Stem part of the display is the leading digit for the data (such
- as 5 in 54) and the leaf is the trailing digit (such as the 4 in 54).
- When larger numbers are used, the rightmost digits are often ignored.
- For example, if the numbers range from 241 to 845, the stem might be
- the 2 to 8, representing 200 to 800, and the leaf would be 0 to 9,
- representing the 10's. The 1's place would be ignored. KWIKSTAT gives
- you options for choosing the magnitude of the stem and leaf values.
-
- DESCRIPTIVE AND COMPARATIVE GRAPHS
-
- The Graphs - Descriptive and Comparative module allows you to create a
- number of different charts and graphs.
-
- CREATING A BAR, LINE OR AREA CHART
-
- The Bar/Line Area chart option allows you to create a graph using any
- combination of these kinds of charts. You can also choose other
- options for this graph as discussed later in this section. The
- following two examples show you how to display a bar chart by creating
- a new database using a current database.
-
- BAR CHART EXAMPLE 1
-
- Step 1 Create the database: Create the database and enter the data.
- Your database should contain a Label field and a Value field (the
- value field contains the numbers to use for the plot.) You can use the
- "SIMPLE BAR CHART" pre-defined structure when creating a new database
- for this graph. For this example MAGNET is the LABEL field and NAILS
- is the VALUE field.
-
- ----These are the fields.-----
- RECORD LABEL VALUE
- ------ ------
-
- 1 SMALL 31 -+
- 2 MEDIUM 38 |--- This is the data to plot.
- 3 LARGE 51 -+
- |
- +----------------- These are the plot labels.
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
-
- Step 2 Enter the Data: Enter the 3 records shown above.
-
- Step 3 Choose Analysis option: Choose the Graphs option from the
- ANALYZE menu.
-
- Step 4 Choose the analysis type: Choose the "Bar/Line/Area" option
- from the Graphs menu.
-
- Step 5 Choose the field to graph: Since there is only one numeric
- field, KWIKSTAT automatically select the Data field.
-
- The resulting chart contains 3 bars labeled SMALL, MEDIUM & LARGE.
- (You could also use this same data to create a pie chart.
-
- BAR CHART EXAMPLE 2
-
- This example will use data already in the database named BARCHART.
- When creating a bar/line/area chart, you can choose more than one
- value field and create a side-by-side bar chart, a stacked bar chart,
- a line chart, an area chart, a point chart, or a chart containing a
- mixture of these types. The data in this example will be used to
- create a chart that includes 2 bars and a line graph.
-
- Step 1 Open the database: Open the database named BARCHART.
-
- Step 2 Choose fields: Choose the fields VAR1, VAR2 and VAR 3 as the
- data fields, then choose "Finished Choosing Fields." Select LABEL as
- the label field. A chart will appear containing three side-by-side
- bars.
-
- Step 3 Choose <options> from the graph menu: An option screen will
- appear that allows you to enter a title, footnote and other options.
- At the bottom of the screen choose <PgDn-Next>. This will display the
- second option screen. See "Options While Displaying a Bar Chart"
- below.
-
- Step 4 Choose types: For Var3 choose the W (Wide Line) type by
- entering a W in the Type column or by clicking on the option until a W
- appears.
-
- Step 5 Display plot: Choose (F7-Continue) to display the plot. You can
- use the <get color> option to select whether the bars will use colors
- or tile patterns.
-
- Your chart can contain any combination of bars, lines, area and point
- charts.
-
- While displaying a bar chart, you can choose from a number of
- options. Some of these options are:
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
-
- <options> from the menu at the top of the screen, and a two-screen
- option form will appear. On the first screen of the form, you can
- specify the axes labels, footnotes, and whether the bars should be
- stacked.
-
- Select the <Next> option to display the second screen option form.
-
- On this form you can specify :
-
- Legend - For each bar/line etc.
-
- Type - choose from Bar, Line, Wide Line, Area or Point
-
- Cumulative - Yes or No
-
- Color or Patterns - Choose from 14 colors or 10 patterns. Patterns are
- displayed if the Tile option has been chosen from the main graph menu.
-
- Display Counts - Yes or No
-
- By clicking on the the Type, Cumulative or Display counts option, the
- options will cycle through the list of options. For Legend, Colors or
- Patterns, enter the desired or color or pattern number. After making
- changes in the options, display the chart by selecting <<F7 -
- Continue>> option.
-
- CREATING A PIE CHART: A pie chart is created from a list of counts.
- (See Help)
-
- CREATING A TIME SERIES/LINE PLOT: A time series plot is useful in
- examining data that are time related, such as profit by month, etc.
- (See Help)
-
- CREATING AN XY PLOT (SCATTERPLOT): An XY plot (scatterplot) displays
- the relationship between two variables. (See Help)
-
- PRODUCING A HISTOGRAM: A histogram can be helpful in determining if
- the distribution of a continuous variable is approximated by a normal
- distribution. (See Help)
-
- DISPLAYING BY-GROUP PLOTS: By Group plots allow you to display graphs
- that show comparisons across groups. (See Help) Types of plots you
- can display in by-group plots include:
-
- A) Box Plot Comparison
- B) Dot Plot Comparison
- C) Mean and Error Bar Comparison
-
-
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- 3-D SCATTERPLOT/ SPIN PLOT
-
- The KWIKSTAT "SPIN" module allows you to interactively view three
- dimensional (XYZ) scatterplots and allows you to rotate the plot
- along the x, y, or z axes, spin the data, and choose other display
- options.
-
- CREATING A SPIN PLOT
-
- The Spin Plot procedure expects your database to contain at least
- three numeric fields and (optionally) a group field. From these
- fields, it can display a three dimensional XYZ plot. For example,
- using the CAR database, follow these steps to create a graph:
-
- Step 1 Open the database: From the main KWIKSTAT FILE menu, open the
- database named CAR. Or, if you are already in the SPIN module, open
- the database by selecting the "ChooSe a database to open" option.
-
- Step 2 Begin the Spin module: If you have not already done so, begin
- the Spin plot module by choosing the Spin Plot option from the ANALYZE
- pull-down menu. The Spin Plot module menu will be displayed.
-
- Step 3 Select the plot type: From the Spin Plot menu, choose choose
- the "3D XYZ Data visualization plot."
-
- Step 4 Select the fields to plot: A pick list of fields will appear
- allowing you to choose three data fields, and optionally, choose a
- grouping field. For the CAR database, choose the following fields (in
- this order) MPG, WEIGHT and HP. For the grouping field, choose
- CYLINDERS.
-
- Note: When a grouping variable is used, the points on the plot will be
- displayed where points for each different group (up to 10 groups) will
- appear in different colors or points for different groups will be
- displayed using a different shaped point (such as a circle, square,
- diamond, etc.) Once you have chosen the fields, an initial plot
- appears.
-
- Step 5 Spin the Plot: To examine the relationships between the
- variables, spin the plot on one or more axes to view the relationships
- from different angles by pressing an arrow key or PgUp or Pg Dn or
- click on the Spin menu options.
-
- SPIN PLOT MANIPULATION OPTIONS
-
- Manually rotate the plot (up-, down-, left- and right-arrow, PgUp and
- PgDn keys) by choosing Roll, Pitch or Yaw. Either point to one of
- these options with the mouse and click, or press the designated
- keyboard button to choose one of these options. Click and hold on a
- spin option and the plot will continue spinning until you let up on
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- the mouse button.
-
- Automatically spin the plot by pressing CTRL, plus a Roll, Pitch or
- Yaw button (i.e., CTRL-rightarrow). Stop the spinning plot by pressing
- a Roll, Pitch or Yaw button (without CTRL).
-
- Grow or Shrink: + or -
-
- Increase or decrease the degree of move: > or <
-
- USING T-TESTS AND ANOVA PROCEDURES
-
- T-tests and Analysis of Variance (ANOVA) procedures are used to test
- hypotheses about population means using data obtained through random
- sampling of those populations.
-
- EXAMPLE: TWO SAMPLE T-TEST (INDEPENDENT GROUPS)
-
- The data used here are heights of 13 plants grown using two different
- fertilizers. Suppose you want to know if there is a difference in the
- average heights of plants in the two treatment groups.
-
- Data for independent group t-test (fertilizer study)
-
- Present Newer Fertilizer
- 46.2 cm 51.3 cm
- 55.6 52.4
- 53.3 54.6
- 44.8 52.2
- 55.4 64.3
- 56.0 55.0
- 48.9
-
- Step 1 Create a database: See the tutorial example earlier for
- information on how to enter this data into a database.
-
- Step 2 Enter the data into the database.
-
- Step 3 Select the analysis to perform: Choose the t-tests and Analysis
- of Variance (ANOVA) option from the ANALYZE pull-down menu, then
- choose the "Compare independent groups (t-test, ANOVA)."
-
- Step 4 Select the fields to use: Select GROUP as the grouping variable
- and OBS (Height) as the data (response) variable. The results appear
- on the screen.
-
- Step 5 Analyze the results: A menu will appear allowing you to view
- the results or display a graphical comparison. Choose to view the
- results. Exit the viewer by choosing F7-Exit.
-
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- Step 6 View the graphical comparison: Select "Graphical Comparison"
- from the options menu to display a comparison of the results. This is
- the same graph described earlier in the section "Displaying By Group
- Plots." Initially, this plot shows an error bars comparison. Exit the
- viewer by choosing the <Exit> option.
-
- EXAMPLE: SINGLE FACTOR ANOVA
-
- When more than two independent groups are compared with respect to one
- variable, one-way or single factor analysis of variance techniques are
- appropriate. This example uses data for hogs which have been randomly
- assigned to four groups, with each group being given a different feed.
- The response is weight gain.
-
- Data for Independent Group ANOVA
-
- Gp 1 Gp 2 Gp 3 Gp 4
- 60.8 78.7 92.6 86.9
- 67.0 77.7 84.1 82.2
- 54.6 76.3 90.5 83.7
- 61.7 79.8 90.3
-
- The database to analyze this data is similar to the one used for the
- t-test example above, differing only with respect to the number of
- groups. In fact, this one-way ANOVA is an extension of the t-test when
- there are three or more groups. To perform this analysis, use these
- steps:
-
- Step 1 Create or Open a database: Create a database using the "FOR
- INDEPENDENT GROUP T-TEST OR ANOVA" pre-defined structure. GROUP will
- be the grouping field. The groups will be numbered 1,2,3,4 according
- to the type of feed used. The response field will be OBS. Or, open the
- database named HOG, and skip to step 3.
-
- Step 2 Enter the data: The data, as entered into the database will
- look like this:
-
-
-
-
-
-
-
-
-
-
-
-
-
-
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- RECNO GROUP OBS (WEIGHT)
- 1 1 60.8
- 2 1 67.0
- 3 1 54.6
- 4 1 61.7
- 5 2 78.7
- 6 2 77.7
- 7 2 76.3
- 8 2 79.8
- 9 3 92.6
- 10 3 84.1
- 11 3 90.5
- 12 4 86.9
- 13 4 82.2
- 14 4 83.7
- 15 4 90.3
-
- Step 3 Select the analysis to perform: Choose the t-tests and Analysis
- of Variance (ANOVA) option from the ANALYZE pull-down menu, then
- choose the "Compare independent groups (t-test, ANOVA)."
-
- Step 4 Select the fields to use: Select GROUP as the grouping field
- and OBS (Weight) as the response variable. The results appear on the
- screen.
-
- Step 5 Analyze the results: The results of this test are summarized in
- the p-value. In this case, the small p-value (p<<0.001) means that
- there is a significant difference between groups. This is taken as
- evidence of a "real" difference between feeds, a difference not due to
- chance.
-
- The ANOVA tells you only that there is a difference among the feeds.
- In order to find out which groups are significantly different from
- which others, examine the multiple comparison results. The
- Newman-Keuls multiple comparison test (or whichever you specified at
- setup) will describe which of the means are significantly different
- from which others (at the 0.05 significance level). One part of the
- output is the multiple comparison test. The test performed depends on
- what option you chose during setup. This example will describe the
- results of the Newman-Keuls test. The results of this test are as
- follows:
-
- Gp Gp Gp Gp
- 1 2 4 3
- -------
- ----
- ----
-
- The group numbers are given in increasing order of the value of their
- group means. That is, Group 1 has the smallest mean, Group 3 the
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-
- 40
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-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- largest. At the 0.05 significance level, the means of any two groups
- underscored by the same line are not significantly different. This
- display tells you that (at the 0.05 significance level):
-
- 1) The mean for group 1 (feed 1) is statistically significantly less
- than the means for all other groups.
-
- 2) The mean for group 2 (feed 2) is significantly greater than the
- mean for group 1, and significantly less than the means of groups 4
- and 3.
-
- 3) The means for groups 4 and 3 are not significantly different from
- each other, but they are both significantly greater than the means of
- groups 1 and 2.
-
- You can conclude that feeds 3 and 4 are better than feeds 1 and 2, but
- there is not enough evidence to say that either feed 3 or 4 is the
- best overall.
-
- Step 6 View the graphical comparison: Select "Graphical Comparisons"
- from the options menu to display a graphical comparison of the
- results. This is the same graph described earlier in the section "By
- Group Plots." Initially, this plot shows a comparison using error
- bars. This figure shows a box plot comparison. From this plot you can
- visually see that groups 3 and 4 are similar and that group 1 is much
- lower than the rest. Exit the viewer by choosing the <Exit> option.
-
- PARAMETRIC REPEATED MEASURES (PAIRED) ANALYSIS
-
- Repeated measures are observations taken on the same or related
- subjects over time or in differing circumstances. Examples would be
- weight loss, or reaction to a drug across time.
-
- EXAMPLE PAIRED T-TEST
-
- The data in this example are before and after weights for eight
- persons on a diet. Notice that in this case, both data values are
- taken from the SAME entity (person). Follow these steps to perform
- this analysis:
-
- Step 1 Create or Open the database: Use the pre-defined database
- structure named "FOR PAIRED T-TEST OR McNEMAR's TEST." This will
- create a database with the fields REP1 and REP2. The REP1 will be used
- for Before and REP2 will be used for After. Or, open the database
- named DIET, and skip to step 3. Data for paired t-test
-
-
-
-
-
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- 41
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- Person Before After
- 1 162 168
- 2 170 136
- 3 184 147
- 4 164 159
- 5 172 143
- 6 176 161
- 7 159 143
- 8 170 145
-
- Step 2 Enter the data: Enter the data for the eight records. The
- database should look similar to the listing of the data above.
-
- Step 3 Choose the analysis: Choose the t-tests and Analysis of
- Variance (ANOVA) option from the ANALYZE pull-down menu. Then choose
- the "Compare repeated or paired data (t-test, ANOVA)" option from the
- module menu.
-
- Step 4 Select the fields to use: Select REP1 (BEFORE) as the first
- field and REP2 as the second field.
-
- Step 5 Analyze the results: Choose to View the results from the
- options menu. Select "Graphical Comparisons" from the options menu to
- display a graphical comparison of the results.
-
- EXAMPLE ONE-WAY REPEATED MEASURES ANOVA
-
- For more than a pair of repeated measures on the same subject, a
- one-way repeated measures analysis of variance is appropriate. The
- data in this example are repeated measures of reaction times of five
- persons after being treated with four drugs in randomized order.
-
- One-way repeated measures ANOVA data
-
- Person Drug 1 Drug 2 Drug 3 Drug 4
- 1 31 29 17 35
- 2 15 17 11 23
- 3 25 21 19 31
- 4 35 35 21 45
- 5 27 27 15 31
-
- The results of this ANOVA are summarized in the p-value. In this case,
- the small p-value (The (p=)0.000 on the "Repeated Factor" line in the
- ANOVA table.) means that there is a statistically significant
- difference in the mean response times for the four drugs.
-
- The Newman-Keuls multiple comparison test (or whichever multiple
- comparison test you chose at setup) describes which of the means are
- significantly different from which others (at the 0.05 significance
- level). See previous ANOVA example.
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- 42
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
-
- SINGLE SAMPLE ANALYSIS
-
- This option allows you to choose a single variable, and test a
- hypothesis that the mean differs from an hypothesized mean. You must
- enter the hypothesized population mean.
-
- DUNNETT'S TEST
-
- Dunnett's test is a multiple comparison procedure following a one-way
- ANOVA that compares a control mean with the other means in the
- analysis.
-
- NON-PARAMETRIC PROCEDURES
-
- Non-parametric procedures are appropriate when the assumption of
- normality cannot be made for a small data set or when a large data set
- is known to be from a non-normal population. Non-parametric procedures
- are generally based on ranks rather than actual data values, so these
- procedures can be useful also when actual data values are not known,
- but the order or ranks of the data values are known.
-
- MANN-WHITNEY PROCEDURE
-
- If two independent groups, such as in this example, are being
- compared, the Mann-Whitney U-statistic is calculated.
-
- EXAMPLE: MANN-WHITNEY TEST OF TWO INDEPENDENT GROUPS
-
- The fertilizer data from the t-test example are used in this example.
- If you have not already created the database for this data set, do so
- now by referring to that example. Follow these steps to do this
- example:
-
- Step 1 Open the database: Open the database named FERTILIZ and choose
- the Non-Parametric Comparisons option from the ANALYZE menu. Or, if
- you are already in the Non-Parametric module, select the "ChooSe a
- Database" option and open the FERTILIZ database.
-
- Step 2 Select analysis type: From the Non-Parametrics Comparisons menu
- select "Independent groups - Mann-Whitney, Kruskal-Wallis."
-
- Step 3 Select fields to use: Choose GROUP as the grouping variable
- and OBS (HEIGHT) as the data (response) variable.
-
- Step 4 View the results: KWIKSTAT will display the results, including
- the Mann-Whitney U statistic, the rank sums, sample sizes and mean
- ranks of the groups, a z statistic and an approximate p-value. In this
- case, U'=24.00, U = 16, z=0.357 and p=0.721.
-
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-
- 43
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- The p-value of 0.721 is large so the null hypothesis of no difference
- in medians between groups is not rejected. There is not sufficient
- evidence based on this procedure to say that there is a difference
- between the median heights of plants in the two groups grown using
- different fertilizers.
-
- KRUSKAL-WALLIS PROCEDURE
-
- If more than two independent groups are being compared using
- non-parametric methods, KWIKSTAT uses the Kruskal-Wallis test. The
- database used is of the same form as for the one-way independent
- gropu analysis of variance.
-
- KWIKSTAT will display the Kruskal-Wallis H-statistic, the rank sums,
- sample sizes and mean ranks of the groups, a chi-square statistic and
- an approximate p-value, and a graph of the results similar to the
- one described for the one-way ANOVA.
-
- NON-PARAMETRIC REPEATED MEASURES ANALYSIS - FRIEDMAN'S TEST
-
- When repeated observations are taken on the same subject, and there is
- interest in comparing the observations for each repeated measure
- (e.g., each type of treatment), then a repeated measures analysis may
- be appropriate. Data for Friedman's test is the same as described in
- the one-way repeated measures ANOVA. The results include a multiple
- comparison of groups.
-
- NON-PARAMETRIC DICHOTOMOUS DATA ANALYSIS - COCHRAN'S Q
-
- Cochran's Q procedure is a non-parametric procedure appropriate for
- use with dichotomous data when the experiment involves repeated
- measures on blocks. The response of the subjects to the treatments is
- dichotomous if it is taken as one of only two possible outcomes, often
- labeled "success" and "failure", rather than as a measurement.
-
- USING REGRESSION & CORRELATION PROCEDURES
-
- To examine the linear relationship between variables, correlation and
- linear regression are used.
-
- SIMPLE LINEAR REGRESSION ANALYSIS
-
- Data for this example of simple linear regression are Homicide Rate
- and Handgun Licenses Issued per 100,000 population for the years 1961
- to 1973 in Detroit (Fisher, 1976, reprinted from Gunst and Mason,
- 1980).
-
-
-
-
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- Data for simple linear regression (handgun study)
-
- Year Homicide Handguns
- Rate Registered
- 1961 8.60 178.15
- 1962 8.90 156.41
- 1963 8.52 198.02
- 1964 8.89 222.10
- 1965 13.07 301.92
- 1966 14.57 391.22
- 1967 21.36 665.56
- 1968 28.03 1131.21
- 1969 31.49 837.60
- 1970 37.39 794.90
- 1971 46.26 817.74
- 1972 47.24 583.17
- 1973 52.33 709.59
-
- Since you want to compare the homicide rate with handguns registered,
- you need a database with only these two sets of numbers (you can
- exclude year.) The data for this example is stored on your disk as
- HANDGUNS.DBF with the variables HOMICIDES and HANDGUNS. See chapter 2
- if you need information about how to create a database. To perform a
- simple linear regression using this data, follow these steps:
-
- Step 1 Open the database: Open the database named HANDGUNS. If you are
- at the main menu, select the Open a Database option from the FILE
- menu, then choose Regression and Correlation from the ANALYZE menu. If
- you are in the Regression module, select "ChooSe a Database."
-
- Step 2 Select analysis type: From the Regression menu, choose the
- "Simple Linear Regression" option.
-
- Step 3 Select the fields to use: Select HOM_RATE as the DEPENDENT (Y)
- variable first, then select HAND_REG as the INDEPENDENT (X) variable.
-
- Step 4 View the results: KWIKSTAT will perform calculations and
- display a menu. Choose "View/Print Results," which will display
- information as shown in figure 4.21. Exit the viewer with F7/Exit.
-
- Step 5 View the Plots: View a scatterplot of the original data with
- the fitted regression line, and a plot of the residual values by
- choosing "Display Plot" items from the options menu.
-
- Step 6 Forecast new values: You may optionally want to predict new
- values from the calculated regression line. If so, choose that option,
- and enter the number or range of numbers of the Independent variable
- you want to use to predict.
-
- Pearson's correlation coefficient (r) is reported (0.7263) as well as
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- 45
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-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- R2 (R-Square, 0.5275). The linear regression equation given is a
- mathematical representation of a straight line that passes through a
- plot of the data, and can be used to predict the dependent variable
- (HOMICIDES) given a value for the independent variable (HANDGUNS). In
- this case the linear regression equation is:
-
- HOMICIDES = 4.910512 + 3.761144E-02 * HANDGUNS
-
- If you want to predict the homicide rate for 300 handguns registered,
- you would use the equation:
-
- HOMICIDES = 4.910512 + 3.761144E-02 * 300
-
- A t-test is performed to test the statistical significance of the
- linear relationship between the two variables. A low p-value means
- that the two variables are significantly related.
-
- Regression Plots: These plots are helpful to determine if a linear fit
- to the data is appropriate. The scatterplot shows you how compact or
- spread apart the points are around the fitted lines, and may help you
- discover outliers. The residual plot helps you determine if a linear
- fit is appropriate.
-
- Predicting new values: When you choose this option, you will be
- prompted for one or more X variable values for which you wish to
- predict Y variable values.
-
- MULTIPLE REGRESSION ANALYSIS
-
- Multiple regression is an extension of simple linear regression into
- several dimensions (several independent variables). In the multiple
- regression procedure, you must enter a list of the independent
- variables and a single dependent variable on which you wish to perform
- the regression analysis. In KWIKSTAT you may use up to 10 independent
- variables in this option. Multiple regression can be complicated.
-
- KWIKSTAT calculates and displays several results, including the
- coefficients and intercept of the regression "line". A significance
- test is performed to determine the significance of the contribution of
- the different variables or factors to the model (mathematical
- representation).
-
- EXAMPLE MULTIPLE REGRESSION ANALYSIS (LONGLEY DATA)
-
- Longley introduced a data set which has often been used in comparing
- multiple linear regression procedures in the literature. The variables
- refer to economic factors. This example uses the LONGLEY database on
- the KWIKSTAT disk. Follow these steps to perform a multiple linear
- regression:
-
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- 46
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- Step 1 Open the database: Open the database named LONGLEY. If you are
- at the main menu, select the Open a Database option from the FILE
- menu, then choose Regression and Correlation from the ANALYZE menu. If
- you are in the Regression module, select "ChooSe a Database."
-
- Step 2 Select analysis type: From the Regression menu, choose the
- "Multiple Linear Regression" option.
-
- Step 3 Select the fields to use: The LONGLEY database consists of 7
- fields: DEFLATOR, GNP, UNEMP, ARMED, POP, TIME, and TOTAL. The first
- six of these will be used as independent variables and the seventh,
- TOTAL, is the dependent variable (the one to be predicted). Select
- TOTAL as the DEPENDENT variable and DEFLATOR, GNP, UNEMP, ARMED, POP,
- TIME as the INDEPENDENT variables, then select "Finished Choosing
- Fields."
-
- Step 4 View the results: KWIKSTAT will perform calculations and
- display the results as shown in figure 4.22
-
- The table at the top of the output (in Figure 4.22) tells you the
- intercept value and the coefficient values for each of the independent
- variables. These can be used to create an equation for prediction of
- the dependent variable.
-
- In this case, the equation is:
-
- TOTAL = -3481930.1065 + DEFLATOR*(15.0161517122) +
- GNP*(-0.03579443400) + UNEMP*(-2.0199053296) + ARMED*(-1.0332049046) +
- POP*(-0.05130725587) + TIME*(1828.99249535)
-
- Note: Although the results are reported to 8 to 9 decimal places, it
- is usually not appropriate or necessary to use this many decimal
- places. After viewing or printing the results, exit the viewer.
-
- Step 5 View the Plots: From the options menu, you can choose to view
- residual plots to determine if the data are linear. If the residual
- plots do not show random patterns, you should determine if there is a
- transformation you can perform on the data to make it linear.
-
- Step 6 Forecast new values: From the options menu, you can choose to
- predict new values from the calculated regression line.
-
- KWIKSTAT also reports R-Square, which gives you a measure of how well
- the regression "line" fits the data.
-
- It is a good idea to view plots of residuals. The plots are helpful to
- determine if regression analysis is appropriate. A pattern other than
- a random horizontal band about zero indicates that the assumptions
- necessary for a regression procedure may be violated.
-
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- 47
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-
- KWIKSTAT 4.1 Statistical Data Analysis
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-
- CORRELATION ANALYSIS
-
- The correlation coefficient is a measure of the strength of the linear
- relationship between two variables. KWIKSTAT allows you to find both
- Pearson's and Spearman's (rank) correlation coefficients of two
- variables. It also displays the matrix of correlation coefficients of
- pairs of variables when there are more than two variables being
- considered.
-
- This example uses the Longley data described in the Multiple
- Regression example above. To display the correlation matrix, use these
- steps:
-
- Step 1 Open the database: Open the database named LONGLEY.
-
- Step 2 Select analysis type: From the Regression menu, choose the
- "Correlation Matrix" option.
-
- Step 3 Select the fields to use: The LONGLEY database consists of 7
- fields: DEFLATOR, GNP, UNEMP, ARMED, POP, TIME, and TOTAL. Select all
- the fields for this analysis. KWIKSTAT will perform the calculations
- and display a 7 by 7 matrix.
-
- Only half of the array is displayed since the other half is a mirror
- image. The diagonal entries are also omitted since they are all one; a
- variable is always perfectly correlated with itself.
-
- Each entry in the array consists of two numbers (three numbers if the
- information is printed to a printer). The first (upper) is the
- Pearson's correlation coefficient for the two (row and column)
- variables of that entry. The second (middle) number, in parentheses,
- is the p-value of the t-test for Ho: rho = 0 vs. Ha: rho <> 0. In the
- hard copy printout (if requested), the third (bottom) number, in
- brackets, is the sample size, or number of paired observations used in
- the calculations.
-
- EXAMPLE GRAPHICAL CORRELATION MATRIX (LONGLEY DATA)
-
- This example uses the Longley data used in the previous example. To
- perform this analysis follow these steps:
-
- Step 1 Open the database: Open the database named LONGLEY.
-
- Step 2 Select analysis type: From the Regression menu, choose the
- "Graphical Correlation Matrix" option.
-
- Step 3 Select the fields to use: The LONGLEY database consists of 7
- fields: DEFLATOR, GNP, UNEMP, ARMED, POP, TIME, and TOTAL. Select all
- the fields for this analysis. KWIKSTAT will perform the calculations
- and display the scatterplots.
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-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
-
- These scatterplots are a visual way of examining the relationships
- between pairs of variables. It allows you to determine if a
- relationship exists between the variables, and allows you to see if
- that relationship is linear. You can use this graphical correlation
- matrix to examine the relationships between variables before using
- them in a multiple regression analysis.
-
- USING FREQUENCY AND CROSSTABULATION PROCEDURES
-
- The Crosstabulations, Frequencies, Chi Square module performs analyses
- on categorical data, that is, data observed in categories, rather than
- measurement data.
-
- EXAMPLE: FREQUENCY TABLE, BAR AND PIE CHARTS
-
- This example uses the EXAMPLE database file. One of the fields
- (variables) in this database is STATUS referring to socioeconomic
- status. Suppose you want to know how the total data set is divided up
- into the five levels of STATUS. You also want to produce a visual
- display of this information. To perform this analysis follow these
- steps:
-
- Step 1 Open the database: Open the database named EXAMPLE, then
- choose the Crosstabulations, Frequencies, Chi Square option from the
- ANALYZE menu. If you are already in the Crosstabulations, Frequencies,
- Chi Square module, select the "ChooSe Database" option.
-
- Step 2 Choose the analysis type: Select the "Frequencies" option from
- the Crosstabulations, Frequencies, Chi Square module menu .
-
- Step 3 Select field: You will be prompted to select one field
- (variable) to use. Since you want to do a frequency table on STATUS,
- select STATUS from the field list.
-
- Step 4 View results: When you choose to view/print the results, a
- frequency table is displayed as shown in figure 4.26. Exit the viewer
- with F7.
-
- If you select "Pie Chart," a pie chart, as described earlier in this
- chapter (Graph Module) will be displayed. If you choose "Bar Chart," a
- bar chart as described earlier in this chapter will appear.
-
-
-
-
-
-
-
-
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- PERFORMING A GOODNESS OF FIT ANALYSIS
-
- A goodness-of-fit test of a single population is a test to determine
- if the distribution of observed frequencies in the sample data closely
- matches the expected number of occurrences under a hypothetical
- distribution of the population.
-
- According to a genetic theory, crossbred pea plants show a 9:3:3:1
- ratio of yellow smooth, yellow wrinkled, green smooth, green wrinkled
- offspring. Out of 250 plants, under the theoretical ratio
- (distribution) of 9:3:3:1, you would expect about
-
- (9/16)x250=140.625 yellow smooth peas,
- (3/16)x250=46.875 yellow wrinkled peas
- (3/16)x250=46.875 green smooth peas
- (1/16)x250=15.625 green wrinkled peas
-
- After growing 250 of these pea plants, you observe that
-
- 152 have yellow smooth peas
- 39 have yellow wrinkled peas
- 53 have green smooth peas
- 6 have green wrinkled peas
-
- To perform this analysis, use the following steps:
-
- Step 1 Select the analysis type: From the Crosstabulations,
- Frequencies, Chi Square menu choose the "Goodness-of-Fit" option.
-
- Step 2 Enter the data: You will be prompted to enter the number of
- categories. In this case, type 4 for the four categories of peas
- (yellow smooth, yellow wrinkled, green smooth, green wrinkled) and
- press Enter. You will also be asked if you want to enter the expected
- ratios, or if you will be entering the actual expected values into the
- table. If you choose to enter ratios, you will enter
-
- 9,3,3,1
-
- An empty table will appear with the instructions to enter the observed
- values for each category. Enter the observed values given above,
- pressing Enter after each entry. For example, for the first row, enter
- 152 for observed (Press Enter) enter 39 (Press Enter) and so on.
- KWIKSTAT will perform the calculations (including filling in the
- expected values column) and display the results.
-
- The calculated chi-square statistic in this case is 8.97 and the
- p-value is 0.031. At a 0.05 level of significance, this p-value
- indicates that there is enough evidence to reject the null hypothesis
- that the observed values follow the theoretical distribution. That is,
- the test (at the 0.05 significance level) suggests that a 9:3:3:1
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- ratio of yellow smooth:yellow wrinkled:green smooth:green wrinkled
- peas is not an appropriate distribution for the population from which
- these data are taken.
-
- PERFORMING A CROSSTABULATION ANALYSIS (CHI-SQUARE)
-
- Crosstabulations can be used to perform a chi-square test for
- independence or a chi-square test for homogeneity. A two-way table is
- constructed that displays the number of counts for each category.
- Crosstabulation table options you may choose for constructing a table
- include:
-
- A) Frequencies only
- B) Include Expected Values
- C) Include Expected Values and Percents
- D) Include Expected Values, Chi-Contribution and Percents
- E) Include Percents
- F) Include Expected Values and Chi-Contribution
- Q) Quit this option
-
- EXAMPLE: 2 BY 2 CROSSTABULATION TEST FOR INDEPENDENCE
-
- Data for this example are observations of the number of beetles and
- bugs on the upper and lower sides of leaves (Zar,1974, page 292).
-
- 2 by 2 Contingency Table Data
-
- Beetles Bugs
- ---------------
- Upper Leaf 12 7
-
- Lower Leaf 2 8
-
- Since you are given only the totals for each of the four categories,
- and not the individual data for each leaf, there is no need to create
- a database. Rather, you can just enter these totals from the keyboard.
- To perform this analysis, follow these steps:
-
- Step 1 Choose analysis type: From the Crosstabulations, Frequencies,
- Chi Square menu, select the "Crosstabulations, Chi-Square" option. You
- will be asked if you want to "Read data from the database" or "Enter
- data from the keyboard." For this example, select "K" to enter data
- from the keyboard.
-
- Step 2 Select size of table: You will then be prompted to give the
- size of the table. When asked for the number of rows, type 2 and press
- Enter. When asked for the number of columns, again type 2 and press
- Enter. An empty table will appear with the instructions to enter the
- counts for each category into the appropriate cell.
-
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- Step 3 Enter the data: Enter the values given above, pressing Enter
- after each entry. KWIKSTAT will perform the calculations and display
- the results.
-
- The calculated chi-square statistic in this case is 4.89 with a
- p-value of 0.028. The chi-square with Yates correction is 3.31 with a
- p-value of 0.069 and the Fisher Exact Test (two tail) has a p-value of
- 0.050. Because one of the cells produces an expected value less than
- 5, KWIKSTAT gives a warning that the chi-square analysis for this data
- may not be valid. Given this warning, it is best to rely on the
- Fisher's Exact Test for making a decision.
-
- EXAMPLE: ANALYZING A LARGER TABLE (SEX BY HAIR COLOR)
-
- A generalization of the 2 by 2 table is the R by C (Rows by Columns)
- table. This is an example (Zar, 1984, page 62) of a two by four
- contingency table involving the variables hair color and sex. The null
- hypothesis is that there is no relationship between hair color and
- sex.
-
- 2 by 4 Contingency Table Data (sex by hair color)
-
- HAIR COLOR
- Sex Black Brown Blonde Red
- -----------------------------------------
- Male 32 43 16 9
- Female 55 65 64 16
-
- Since you are given only the totals for each of the eight categories,
- and not the individual data for each person, there is no need to
- create a database. Rather, you can just enter these totals from the
- keyboard. To perform this analysis, follow these steps:
-
- Step 1 Choose analysis type: From the Crosstabulations, Frequencies,
- Chi Square menu, select the "Crosstabulations, Chi-Square" option. You
- will be asked if you want to enter data from a (D)atabase or
- (K)eyboard. Type K and press Enter.
-
- Step 2 Select size of table: You will then be prompted to give the
- size of the table. When asked for the number of rows, enter 2. When
- asked for the number of columns, enter 4. An empty table will appear
- with the instructions to enter the counts for each category into the
- appropriate cell.
-
- Step 3 Enter the data: Enter the values given above, pressing Enter
- after each entry. KWIKSTAT will perform the calculations and display
- the results.
-
- Step 4 Analyze the results: The calculated chi-square statistic in
- this case is 8.99 with a p-value of 0.03. A decision can be made using
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- this p-value of the test. A low p-value (less than the chosen
- significance level) is usually taken to indicate rejection of the null
- hypothesis.
-
- CREATING A 3-D BAR CHART
-
- As an option when performing a Crosstabulation, KWIKSTAT allows you to
- draw a 3-dimensional bar chart of data for a contingency table
- (crosstabulation), and then to focus in on a part of it if desired.
- Data for the 3-dimensional bar chart must be entered first, either
- from the keyboard or a database, by using the "Crosstabulations,
- Chi-Square" option.
-
- MCNEMAR'S TEST
-
- McNemar's test is appropriate for use with paired, dichotomous data.
- This test is sometimes called a test for related samples or a test for
- the significance of changes. It is useful for comparing paired or
- related observations in which the response is dichotomous, that is,
- the response is one of only two possible outcomes. McNemar's test is
- the 2 by 2 version of Cochran's Q test described in the section on
- non-parametric tests. The test assumes that any pair of observations
- is independent of any other pair of observations, although clearly the
- observations within a pair are not independent of each other.
-
- LIFE TABLES AND SURVIVAL ANALYSIS
-
- Survival Analysis is used to analyze the survival experience of a
- group of persons or components. In medical research, survival analysis
- is helpful is studying the survival of patients under one or more
- conditions. In industry, the survival may be that of a component such
- as an electronic switch or a gear. To perform a survival analysis, the
- data must be in the following form:
-
- 1) a TIME variable which contains a time (e.g., minutes, days, years,
- etc.) in which the subject or component has been observed to be alive
- (not failed).
-
- 2) a CENSOR variable which must take on the values 0 or 1, where 1
- means the subject has died (failed), and a 0 means the subject was
- still alive (not failed) at the last available time period.
-
- 3) optionally, a GROUPING variable which may have up to ten values
- (numeric or character), i.e., the data may be in groups.
-
- KWIKSTAT allows you to choose from two types of life tables, Actuarial
- or Kaplan-Meier. The Actuarial method uses fixed length intervals in
- the table, and the Kaplan-Meier table uses intervals based on the
- data.
-
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-
- 53
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-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- Once the data are entered into the program, a life table for each
- group is produced which includes, for each time interval, the number
- entered, withdrawn, lost, dead, exposed, the proportion dead,
- proportion surviving, cumulative proportion surviving, and other
- information.
-
- A plot is given for the cumulative proportion surviving in the
- group(s) against time. If more than one group is entered, a
- Mantel-Haenszel log-rank test is performed to test the hypothesis of
- equal survival patterns for the groups. A reference to how this test
- is developed is covered in Matthews and Farewell (1988).
-
- EXAMPLE: ACTUARIAL LIFE TABLE ANALYSIS
-
- The data for this example are in the LIFE database on the KWIKSTAT
- disk. These data are from Prentice (1973). To perform this analysis,
- follow these steps:
-
- Step 1 Open the database: If you are at the main KWIKSTAT menu, choose
- the Open Database option from the FILE menu and select the database
- LIFE, then choose the Life Table and Survival Analysis option from the
- ANALYZE menu. If you are already in the Life module, open the LIFE
- database by selecting the "ChooSe database to open" option.
-
- Step 2 Choose the analysis type: Select the "Actuarial Life Table
- Analysis" option from the Life Table and Survival Analysis menu. Step
- 3 Choose fields to use: The LIFE database consists of 3 fields:
- SURVIVAL, CENSOR, and GROUP. A portion of the LIFE database is shown
- here:
-
- SURVIVAL CENSOR GROUP
- 72 1 1
- 411 1 1
- 228 1 1
- 11 1 1
- 25 0 1
- 144 1 1
- etc...
-
- The first column is the SURVIVAL field with entries of length of life,
- or length of survival. The second column is the CENSOR field, an
- indicator of whether the subject has failed (died) or not at the last
- observed time period. 1 means failed, 0 means not failed (still
- alive).
-
- The third column contains a grouping variable. In this case it is
- either 1 or 2. Group 1 may represent one treatment, while group 2
- represents another kind of treatment. The objective is to compute
- survival curves to see if the treatments provide different average
- survival distributions.
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-
- 54
-
-
- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
-
- Select SURVIVAL as the TIME variable, CENSOR as the censor variable
- and GROUP as the grouping variable.
-
- Step 4 Select interval length: KWIKSTAT reports the names and sizes of
- the groups and then asks you to specify the length of each interval
- for the table to be produced. You can specify a desired interval
- length or you can use the default length by simply pressing Enter. For
- this example, press Enter to select the default length.
-
- Step 5 Analyze the results: KWIKSTAT will perform the calculations and
- display an options menu. If you choose the View/Print option two sets
- of tables, one for each group will be displayed. The first table
- includes the numbers of subjects entered alive, withdrawn, dead,
- exposed, the proportion dead, proportion alive, cumulative survival
- proportion and standard error for the first group. The second table
- includes 95% confidence limits on the cumulative survival proportion.
-
- From the table, you can see that, in the first group, 22 of 37
- exposed, or 59.5% died in the first interval (0.0-99.0) and two were
- withdrawn. In the second group, 12 of 23.5 exposed (51.1%) died and
- one was withdrawn in the first interval. Exit the viewer by selecting
- F7/Exit.
-
- Comparing Survival Curves: At the end of the report, KWIKSTAT reports
- the results of the Mantel-Haenszel comparison of the two curves. The
- hypotheses being tested are:
-
- Ho: The survival curves are the same.
- Ha: The survival curves are not the same.
-
- In this example, the Mantel-Haenszel comparison procedure results in a
- chi-square statistic of 0.7191 and a p-value of 0.397. This p-value is
- much too large to reject the hypothesis of equal curves. This
- indicates that the two distributions are not statistically
- significantly different - thus neither treatment is superior in terms
- of survival distributions.
-
- Displaying Survival Curves: From the options menu, you can choose to
- display survival curves. This is a graphical representation of the
- cumulative proportion surviving from the life table. The survival
- curve for this analysis is shown.
-
- The Kaplan-Meier life table contains most of the same information as
- the Actuarial Life Table. However, instead of the time intervals being
- fixed, the time intervals are based on time values from the data.
-
-
-
-
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-
- 55
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- ==========
- REFERENCES
- ==========
-
- Box, Jenkins, and Reinsel, Time Series Analysis - Forecasting and
- Control, Prentice-Hall, 1994.
-
- Deming, W.E., Out of Crisis, Cambridge, MA: Massachusetts Institute
- of Technology, Center for Advanced Engineering Study, 1986
-
- Dixon, W.J. and Massey, F.J., Introduction to Statistical Analysis,
- McGraw-Hill Book Company, New York, 1969.
-
- Elliott, A.C. and Woodward, W.A.,"Analysis of an Unbalanced Two-Way
- ANOVA on the Microcomputer", Communications in Statistics, Volume B15,
- Number 1, 1986.
-
- Gunst, R.F., and Mason, R.L., Regression Analysis and its
- Applications, Marcel Dekker, New York, 1980.
-
- Granger, C.W.J. and Newbold, P., Forecasting Economic Time Series,
- Academic Press, 1977.
-
- Hoaglin, D.C., Mosteller, F., Tukey, J.W., Understanding Robust and
- Exploratory Data Analysis, John Wiley & Sons, Inc. New York, 1983.
- (Box and Whiskers Plots, Stem and Leaf Displays)
-
- Kennedy, W. J., Jr., and Gentle, J.E., Statistical Computing, Marcel
- Dekker, Inc, New York, 1980.
-
- Larsen, R.J. and Marx, M.L., Statistics, Prentice-Hall, 1990.
-
- Lehmann, E.L. Nonparametrics: Statistical Methods Based on Ranks,
- Holden-Day, Inc, Oakland, Ca, 1975.
-
- Longley, J.W. "An appraisal of least squares programs for the electronic
- computer from the point of view of the user." JASA, 1967, 62, 819-831.
-
- Montgomery, D.C., Introduction to Statistical Quality Control, John
- Wiley and Sons, 1991.
-
- Neter, J., Wasserman, W., and Kutner, M. H., Applied Linear
- Statistical Models, Richard D. Irwin, Inc., 1990, Third Edition.
-
- Prentice, R.L. "Exponential survivals with censoring and explanatory
- variables.", Biometrika 60, 1973, 279-288.
-
- Ryan, Thomas P. Statistical Methods for Quality Improvement, John
- Wiley & Sons, New York, 1989. Tukey, J.W., Exploratory Data Analysis,
- Addison-Wesley, 1977.
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-
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
-
- Tsay, R.S., and Tiao, G.C., "Consistent Estimates of Autoregressive
- Parameters and Extended Sample Autocorrelation Functions for
- Stationary and Nonstationary ARMA Models," JASA 79, 84-96, 1981.
-
- Winer, B.J., Statistical Principles in Experimental Design, Second
- Edition, McGraw-Hill Book Company, 1971.
-
- Woodward, W.A., Elliott, A.C., Gray, H.L and Matlock, D.C., Directory
- of Statistical Microcomputer Software, Marcel Dekker, New York, 1988.
-
- Woodward, W.A., and Gray, H.L., "On the relationship between the
- S-array and the Box-Jenkins Method of ARMA Model Identification," JASA
- 76, 579-587, 1981.
-
- Zar, J.H., Biostatistical Analysis, Prentice Hall, Inc, 1974 and 1984
- editions.
-
-
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-
-
-
-
-
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-
-
-
-
-
-
-
-
-
-
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- KWIKSTAT 4.1 Statistical Data Analysis
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-
- ===========
- APPENDIX A
- ===========
- INTERPRETING ERROR CODES
-
- While every precaution is taken in writing software, all possibilities
- of use cannot be anticipated. If the program encounters a problem it
- does not know how to resolve, it will usually display an error
- message. This message will contain an error code and a reference code.
- If you encounter an error message, write it down and refer to this
- list to see if you can figure out how to resolve the problem. If you
- are unable to resolve the problem, please write down the steps you
- took before the error was encountered, and send it to TexaSoft on the
- Problem Report Form. We will try to resolve the problem as quickly as
- possible.
-
- Error Number 5 = Illegal function call
- Error Number 6 = Overflow
- Error Number 7 = Out of Memory
- Error Number 9 = Subscript out of range
- Error Number 11 = Division by zero
- Error Number 14 = Out of String Space
- Error Number 24 = Device Timeout
- Error Number 25 = Device fault
- Error Number 27 = Out of Paper
- Error Number 50 = FIELD overflow
- Error Number 51 = Internal Error
- Error Number 52 = Bad filename or number
- Error Number 53 = File not found
- Error Number 54 = Bad file mode
- Error Number 55 = File already open
- Error Number 57 = Device I/O error
- Error Number 58 = File already exists
- Error Number 61 = Disk full
- Error Number 62 = Input past end of file
- Error Number 63 = Bad record number
- Error Number 64 = Bad filename
- Error Number 67 = Too many files
- Error Number 68 = Device unavailable
- Error Number 70 = Permission denied
- Error Number 71 = Disk not ready
- Error Number 72 = Disk media error
- Error Number 74 = Rename across disks
- Error Number 75 = Path/File access error
- Error Number 76 = Path not found
- Error Number 81 = Invalid filename
-
-
-
-
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- PROBLEM REPORT FORM: KWIKSTAT
-
- Please explain in detail the problem that occurred. If possible, send
- a printout of the results or Print Screen if possible.
-
- KWIKSTAT VERSION#_____________ RELEASE#________________
- (see opening screen)
- KWIKSTAT module where problem occurred:______________________
- (It is often helpful if you can indicate the precise commands you
- used leading up to the problem.)
- Your computer brand/model_____________________________________
- (Also indicate if it is a 8088, 286, 386, 486, Pentium)
- Monitor type: (circle one) EGA, or VGA (including SuperVGA)
- Amount of free memory available:____________________
- (use the MEM or CHKDSK command to find this out.)
- Version of DOS you are using:____________________________________
- (Use the VER command to find this out.)
- Memory resident program in use:__________________________________
- Running KWIKSTAT from (i.e DOS, Windows, DOS SHELL):__________
- PROBLEM:
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
- Mail to:TexaSoft, P.O. Box 1169, Cedar Hill, Texas 75106-1169. Or fax to
- 214-291-3400, or send E-Mail to Compuserve 70721,3145 or Internet
- 70721.3145@compuserve.com.
-
-
-
-
-
-
-
-
-
-
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-
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- KWIKSTAT 4.1 Statistical Data Analysis
- --------------------------------------------------------------------
-
- USER'S BALLOT
-
- Please indicate your preference for improvements in KWIKSTAT. On a
- scale of 0 to 10
-
- 0 = Very Low priority for this change
- 10 = Very High priority for this change
-
- Vote Proposed item of change
- ---- ---------------------------------------------------------
- ____ Windows version
- ____ Add more ANOVA types - example:___________
- ____ Add more Non-parametric statistical tests
- ____ Add General Linear Model
- ____ Make Report more flexible
- ____ Add more Quality Control options
- ____ Cluster Analysis
- ____ Discriminant Analysis
- ____ Add other types of analysis - example:__________
- ____ _____________________________________________
- ____ _____________________________________________
- ____ _____________________________________________
- ____ _____________________________________________
- Other Comments:(Your ideas are very important us.)
-
-
-
-
-
-
-
-
- Mail to:TexaSoft, P.O. Box 1169, Cedar Hill, Texas 75106-1169. Fax
- to:214-291-3400 or send E-Mail to Compuserve 70721,3145 or Internet
- 70721.3145@compuserve.com.
-
-
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