Shareware Overload/ShartewareOverload.cdr/finance/cj100.zip/CATJACK.DOC

Text File | 1989-05-22 | 22KB | 541 lines

                                C a t J A C K

               Statistical Calculator

                                      by

                               Brad Strausbaugh
                           350 E. Del Mar Blvd #125
                             Pasadena, Ca  91101


CatJACK is an  easy-to-use  interactive  tool  for  fast  quantitative
analysis  of small data sets.  The statistics available include single
and praired  distribution,  ANOVA,  correlation  and  regression,  and
crosstab analysis.  No knowledge of programming is required.  You will
need only a basic understanding of elementry statistics.


The Shareware Concept

CatJACK is widely available  to  the  public  on  electronic  bulletin
boards and shareware distributors around the country.  You are invited
to share CatJACK with colleagues and/or your local bulletin board.  To
keep  all  the  files  together, please share only the self-extracting
CJ100.EXE.  If you find  CatJACK  useful  in  meeting  you  needs  for
quantitative analysis, please send $20 to the author.

      Brad Strausbaugh
      350 E. Del Mar Blvd #125
      Pasadena, Ca  91101

Your support of the  shareware  concept  helps  insure  the  continued
availability of quality software on a test-drive-first basis.

Shareware distributors are encouraged to copy and  distribute  CatJACK
for  the  few dollars per diskett typical in the shareware marketplace
today.  Charging the author's fee mentioned above is prohibited and in
violation of the copyright.


Getting Started

After extracting CJ100.EXE you will find the following files.

      CATJACK.DOC       This documentation file
      CATJACK.EXE       The CatJACK program
      BRUN30.EXE        The run-time module
      T.TBL             The probablity tables
      F1.TBL
      F5.TBL
      CHISQ.TBL
      STUDENTS          A data file for demonstration purposes
                                                                Page 2


You can invoke CatJACK by setting your default device and subdirectory
to  where  you  are  keeping  these  files, and entering the following
command at a DOS prompt.

      C> CATJACK

After taking a few seconds to load  the  probability  tables,  CatJACK
will  display  the login banner.  Just press any key and you are ready
to start.


The 30 Minute Tour

This document uses the rather un-original example of a junior  college
psychology  class's  data to illustrate CatJACK's operation.  Although
this data has already been created, you will be asked in the next  few
paragraphs  to define and create a portion of it yourself.  Doing this
you will learn to make the best use of CatJACK.


Controlling the CatJACK Environment

Here are a few basic conventions used throughout the CatJACK system.

     1.  The main menu is always present at the  top  of  the  screen.
         The currently active option is highlighted in reverse video.

     2.  You can change the current menu  option  with  the  left  and
         right  arrow  keys  on  the  numeric keypad (be sure the "Num
         Lock" key is off), or by entering the  first  letter  of  the
         option  you  want.   When  the  menu  option  you  want is is
         highlighted, press the Return key to select it.

     3.  The Return key always advances you forward to  the  the  next
         step  while  the  Escape  key allows you to "stepback" to the
         previous step.

     4.  The bottom line of the screen will always  display  pertinent
         help information.



Defining an Array

By way of illustration, let us define an array containing  information
on  our  students  in the junior college psychology class.  We want to
determine (1) if the  distribution  of  our  students'  mid-term  exam
scores,  and  (2)  whether  or  not  there is a significant difference
between the scores of male and  female  students.   I  have  kept  the
sample size small to minimize data entry time.

We begin by selecting the "Define" option from the main menu.  We will
define  a  data  array  with  two variables, Grade and Sex, for our 15
students.  Just think of the array as a  two-dimensional  table  where
each  horizontal  row  represents  a  student and each vertical column
                                                                Page 3


represents a variable.

After selecting "Define", a prompt will appear on line  2  asking  for
the  width  of  the first variable.  Keep the following points in mind
when you select a width.

     1.  Variables can be from 1 to  10  characters  wide  (8  is  the
         default).   This  includes decimal points and signs.  Be sure
         you choose a width that  will  hold  the  maximum  value  you
         expect in your data.

     2.  The width you select to accomodate the variable's  data  will
         also be the maximum width allowed for the variable's name.

Lets make the first variable, Grades, 8 characters wide.  Since  8  is
the default we can just press the Return key at the width prompt.

Next, CatJACK asks for the name we want to give this variable.  Notice
the  space  available  to enter the variable name is only 8 characters
wide, the same as  our  width  selection.   Enter  the  variable  name
"Grade" (without the quotes).

Finally CatJACK asks whether Grade is  a  text  or  numeric  variable.
Data  for  numeric variables is right justified and available for math
operations, while data for text variables is left justified and cannot
be summed, or averaged, etc.  Since we want to perform calculations on
Grade, enter "N" for numeric.

Now our first variable has been defined and its name  appears  in  the
upper left corner of the array editor.  CatJACK now asks if we want to
define another variable.  We  still  have  to  define  a  variable  to
identify each student's sex, so enter "Y" for Yes.

We want the width for this variable to be 3 characters wide, the  name
to  be  "Sex"  and  the data type to be Text.  Go ahead and define the
variable Sex.  Remember, the helpline is always present at the  bottom
of the screen if you get stuck.

This time when CatJACK asks if you want to  define  another  variable,
enter "N" for No.  CatJACK will return you to the main menu.


Entering Data

With an array defined, we are now ready to enter our  students'  data.
Select the "Edit" option from the main menu.

CatJACK  prompts  for  the  grade  of  the  first  student.   It  also
highlights  the  corresponding  cell  on  the  spreadsheet.  The first
student's mid-term exam grade was 96%, so enter "96"  at  the  prompt,
then  press  Return  (Never  enter the percent sign, and never enter a
dollar sign or a pound sign.  The only valid characters for a  numeric
variable are the digits 0 to 9, a decimal point, and sign if needed).

CatJACK then prompts for the same student's Sex.  Enter "M" for  Male,
                                                                Page 4


then press Return.

CatJACK is now awaiting data for the second  student.   Go  ahead  and
enter  data  for the remaining students as shown below.  If you make a
mistake and need to change the data in a certain cell, use  the  arrow
keys to move to that cell, then enter the correct data.  If you get in
trouble, remember the help line at the bottom of the screen.

   Define Edit Save Load Sort Analyze Print Quit


     +- Grade   -Sex--------
     1        96 M
     2        80 F
     3        84 F
     4        90 M
     5        88 F
     6        78 M
     7        86 M
     8        88 F
     9        92 M
    10        90 F
    11        84 F
    12        88 F
    13        68 M
    14        74 F
    15       100 M
    16
    17
     +-------------------

When you are finished press the Escape key to  stepback  to  the  main
menu.

We have kept the number of students in our example down to 15 just  to
minimize  data  entry time.  Your actual data will probably exceed the
17 lines showing in the first spreadsheet window.  CatJACK  allows  up
to  200  lines of data.  The edit window scrolls as needed to show the
current cell.


Single Distribution Analysis

Now we can examine  the  students'  Grade  distribution.   Select  the
"Analyze"  Main  menu  option.   CatJACK  will  ask  whether  we  want
Distribution, ANOVA,  Correlation/Regression,  or  Crosstab  analysis.
Select "Distribution".

CatJACK then asks whether we want a "Single" or "Paired"  distribution
analysis,  Lets  select  "Single" first to see the distribution of the
whole class.

CatJACK prompts for which variable to analyze.  Enter "Grade".  If you
enter  a  variable  that  does not exist, an error message will appear
asking you to reenter the correct variable name.
                                                                Page 5


After a few seconds  CatJACK  will  display  the  Single  Distribution
Analysis  of  the  variable  Grade, This screen shows, the sample size
(n), mean, median, mode, standard deviation (StdDev),  standard  error
of  the  mean  (StdErr), highest, lowest, range, variance and sum.  It
also shows a grouped frequency histogram with mid-point raw score  and
mid-point z score.

Notice the histogram is made up of asterisks (*), one for  each  case.
We  should mention here that if the mode of a distribution exceeds 15,
each asterisk will represent more than one case.  Just how many  cases
each  asterisk represents depends on how many multiples of 15 the mode
exceeds.  In such  cases  the  histogram  may  show  a  group  with  a
frequency  greater  than  1 but no asterisks.  The histogram should be
used only to get a general picture of the distribution curve.

If you want to send this display to your printer  select  the  "Print"
option  from the line-2 menu.  The "Print" option is available for all
analysis screens.  When you are finished select the "Menu" option,  or
just press the Escape key to stepback to the distribution menu.


Paired Distribution Analysis

We can compare the  mid-term  grades  of  male  and  female  students.
Stepback  to  the  Distribution  menu  with  the Escape key and select
"Paired".

At the appropriate prompts select "Sex" as the  independent  variable,
and  "Grade"  as  the dependent variable.  For the independent group x
enter "F" (Female), and the independent group y enter "M" (Male).

After a few seconds  CatJACK  will  display  the  Paired  Distribution
Analysis of Grade by Sex.

In addition to the  statistics  we  saw  in  the  Single  Distribution
Analysis,  we also see the t-ratio, degree of freedom (d.f.) and p for
both the one and two tailed probability distributions.  The  histogram
shows  occurrences  of  the x variables as "x", the y variable as "y",
and were both occur, "#",



Adding New Variables To The Current Data Array

Suppose that instead of comparing the mid-term exam grades by Sex,  we
want  to  compare  them, by the students' high schools.  To do this we
will add a new variable to the array.  We will name it "HS"  for  High
School.

Stepback to the main menu with the Escape  key  and  select  "Define".
Since  CatJACK now has our current array in memory, it asks whether we
want to "Create" a new array or "Modify" the current one.  We want  to
add  a variable to the current array so select "Modify".  Then CatJACK
asks if we want to "Add" a new variable or "Delete" an  existing  one.
Select "Add".
                                                                Page 6


Subsequent prompts should look familiar.  They are  the  Width,  Name,
and  Text/Numeric  prompts  we've  seen  before.   Define the new high
school variable as Width:  2, Name:  HS, and data type T (text).

Now stepback to the main menu and select the "Edit" option.  Using the
arrow  keys  to  position  the  active  cell  on  line  1 under the HS
variable, enter the data into the new variable as shown below.

Terminate each entry with the Down Arrow key instead of the Return key
to stay in the HS column.

By the way, "WY" is for West York, "EY" is for East York, and  "C"  is
for Central.

   Define Edit Save Load Sort Analyze Print Quit


     +- Grade   -Sex-HS-------
     1        96 M   WY
     2        80 F   C
     3        84 F   C
     4        90 M   WY
     5        88 F   EY
     6        78 M   C
     7        86 M   C
     8        88 F   WY
     9        92 M   WY
    10        90 F   EY
    11        84 F   WY
    12        88 F   EY
    13        68 M   EY
    14        74 F   C
    15       100 M   WY
    16
    17
     +-----------------------

When you have entered the high schools, stepback to the main menu with
the Escape key.


Analysis of Variance

Now we can compare grades across high schools.  Since there  are  more
than  two  high schools reprsented in this junior college class we use
"ANOVA".

Select "Analyze" from the main menu, then  "ANOVA"  from  the  analyze
menu.   Enter  "HS"  as  the  independent  variable and "Grade" as the
dependent.

After computing for a few seconds CatJACK  displays  the  Analysis  of
Variance Summary Table which includes the within an between groups sum
of squared deviations from the mean (SS), degree  of  freedom  (d.f.),
mean square (MS), F-ratio, and p.
                                                                Page 7


If you want to see statistics for  each  group  of  students  by  high
school,  select "GroupDetail" from the ANOVA menu.  This display shows
each group's n, mean, standard deviation, and standard  error  of  the
mean.

When you are using ANOVA on your own  data,  keep  in  mind  that  the
maximum number of independent groups allowed is ten.


Saving and Loading Arrays from Disk

We still haven't seen correlation and crosstab analyses.  To  do  that
we  will  need  some  new variables.  Since you now know how to define
arrays and enter data, this would be a good time to look at Saving the
array  you've  just entered to disk and Loading an array I've prepared
for you that contains the new variables.

It is a good habit to save new data  to  disk  immediately  after  you
leave the Edit mode.  In the event of a system failure you can recover
simply by reloading the array from disk.  And if you  are  entering  a
particularly large array you may want to save the array after entering
every twenty lines or so.

First Save your current array to disk.  Use the Escape key to stepback
to  the  main  menu,  then select the Save option.  CatJACK asks for a
name to identify the array when it's on disk.  Enter  the  array  name
"CLASS".  CatJACK will then save your array to disk.

Now you can load the new larger array.  Select the  Load  option  from
the  main  menu.  When CatJACK asks for the name of the array to load,
enter "STUDENTS".  CatJACK will take a few seconds to load  the  array
before it displays it on the spreadsheet.

In addition to the variables you are  familiar  with,  our  new  array
contains  each  student's  GPA and SAT scores.  Notice, also, that the
variable name for HS has been changed to "HighSchool" and its data  is
now spelled out.


Correlation Analysis

Suppose we want to know the extent to which we can predict a student's
mid-term exam grade from his or her GPA.

Select the main menu option "Analyze", then select  the  analyze  menu
option  "Correlation/Regression".   CatJACK  then  prompts  for  which
correlation coefficient to use, Pearson or Spearman.  Since Grades and
GPA  are  interval  data  we  select  "Pearson".   Using  Spearman for
anything other than ranked data will yield erroneous results.

CatJACK then asks for which display you want.  Select "Detail"  (We'll
look  at  the  others  in  a  moment).  Then CatJACK prompts for which
variables to use.  Enter "GPA as the Independent (predictor) variable,
and "Grade" as the dependent variable.
                                                                Page 8


After a few seconds CatJACK displays the Pearson Correlation Analysis.
This  display  includes  the  Pearson  Correlation  coefficient (r), r
Square, standard error of  prediction  (StdErr),  degree  of  freedom,
t-ratio, regression line slope and Y intersect.  It also shows a brief
scatterplot where points are represented as  ".",  ":",  "+",  or  "#"
depending on their frequencies.

Now we can predict a student's likely mid-term exam score from his  or
her  GPA.  Select the line-2 menu option "Predict", then enter the GPA
of a student whose Grade you want to  predict,  say,  "3.2".   CatJACK
will  display the predicted Grade (Y Prime) along with the Grade high,
low, and range for the 99%, 95%, 90%, and 80% confidence levels.

You can compare one numeric variable with all others.   Lets  stepback
to  the  Correlation  menu  using the Escape key, select the "Pearson"
coefficient again, and now select  the  "OneToAll"  display.   At  the
independent  variable  prompt,  enter  "Grade".   CatJACK now displays
statistics  showing  how  Grade  correlates  to  all   other   numeric
variables.

And finally we can see how all  numeric  variables  correlate  to  all
others.  Proceed to the display prompt as before, and this time select
"AllToAll".  CatJACK will display the correlation coefficient  of  all
numeric variables to all others.


Crosstab Analysis

We can examine the contingency of two variables.  Suppose we  want  to
compare  the  frequency  of  male  vs  female  students from each high
school.  Use the Escape key to  stepback  to  the  analysis  menu  and
select  "Crosstab".  Enter "HighSchool" as the X variable and "Sex" as
the Y variable.  After computing  for  a  few  seconds,  CatJACK  will
display  the  Crosstab  Analysis screen, with each cell containing the
observed (O) and theoretical (T) frequencies; and  it  will  show  the
degree of freedom, chi-square, and p.

When you use Crosstab analysis on your data keep  in  mind  that  each
variable can have no more than ten groups.


Sorting

We can sort the data array by any number of variables.   For  example,
suppose  we  want  to sort our students by HighSchool, and within each
HighSchool we want to sort by Grade.

To do this, stepback to the main menu and select  the  "Sort"  option.
CatJACK  will  prompt  for  the variables or "keys" to sort by.  Enter
"HighSchool" and "Grade for keys 1 and 2 respectively.   When  CatJACK
prompts for key 3, just press Return.

After a few seconds CatJACK will display the array in the  sort  order
requested.
                                                                Page 9


Printing the Data Array

To list the entire data array on your printer just select the  "Print"
main  menu  option.  The array will be printed out in the current sort
order with the variables names  appearing  across  the  top  and  line
numbers down the left side.


To Quit from CatJACK

You can terminate your CatJACK interactive session and return  to  DOS
by  selecting  the "Quit" main menu option.  If the current data array
has been changed but not saved to disk, a warning will appear,  asking
if you want to save it before quitting.


Analyzing Data Output by Other Programs

You can use CatJACK to analyze data you  already  have  on  disk  from
other  programs.   This  data  must  have the characteristics outlined
here.  See the example of our STUDENTS file below.

     1.  Variables cannot be more than 10 characters wide.

     2.  Variables must be separated by one space.

     3.  On the first line, an "N" for numeric or "T"  for  text  must
         appear, left justified, over each variable.

     4.  On the second line,  the  variable  name  must  appear,  left
         justified, over each variable.

     5.  On the third line, hyphens must appear across  the  width  of
         each  variable.  This tells CatJACK each variable's start and
         end position.

     6.  From the forth line on the data should appear.  Numeric  data
         must  be  right justified within each variable, and text data
         must be left justified.

     7.  CatJACK allows a maximum of 200 lines of data.

Any  deviation  from  these  characteristics  can  have  unpredictable
results.   You can use your favorite text editor to make the necessary
modifications to your file.  If you are using  a  word  processor,  be
sure it is set to non-document mode.
                                                               Page 10



N        T   T          N        N
Grade    Sex HighSchool GPA      SAT
-------- --- ---------- -------- --------
      96 M   WESTYORK        3.6     1300
      80 F   CENTRAL         3.3     1166
      84 F   CENTRAL         3.4     1210
      90 M   WESTYORK        3.4     1280
      88 F   EASTYORK        3.5     1277
      78 M   CENTRAL         2.7     1120
      86 M   CENTRAL         3.5     1260
      88 F   WESTYORK        3.4     1256
      92 M   WESTYORK        3.6     1380
      90 F   EASTYORK        2.8     1390
      84 F   WESTYORK        3.0     1250
      88 F   EASTYORK        3.1     1310
      68 M   EASTYORK        2.3      824
      74 F   CENTRAL         2.4     1022
     100 M   WESTYORK        3.8     1498



CatJACK

Jack is a brown long-haired Persian cat who kept  me  company  through
the long hours of developing this program.