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users manual
SOFTWARE USER'S MANUAL
Statistical Process Control Software
(SPC Version 1.1)
March 1992
Prepared by:
Mark Shewhart
Air Force Logistics Command
Center for Supportability and Technology Insertion
Process Improvement Division
CSTI/PIAP
Wright-Patterson AFB, Ohio 45433
TABLE OF CONTENTS
#m0#m. OVERVIEW
#m1#m. INTRODUCTION
#m1.1#m Bar Graphs
#m1.2#m Pareto Charts
#m1.3#m Pie Charts
#m1.4#m Scatter Diagrams
#m1.5#m Histograms
#m1.6#m Frequency Polygons
#m1.7#m Ogives (Cummulative Distribution Function)
#m1.8#m Control Charts
#m1.9#m Software Functionality
#m1.9.1#m Control Charts
#m1.9.2#m Other Diagrams and Graphs
#m1.10#m Unique Features of SPC
#m1.11#m SPC Software Support
#m2#m. INSTALLATION
#m3#m. EXECUTION
#m3.1#m Executing Demonstration Program
#m3.2#m Executing SPC Chart Interpretation System Software
#m3.3#m SPC MAIN MENU and STATUS BOX
#m3.3.1#m SPC MAIN MENU Option A : Select Raw Data File
#m3.3.2#m SPC MAIN MENU Option B : Select Chart Type
#m3.3.3#m SPC MAIN MENU Option C : View Chart/Diagram
#m3.3.4#m SPC MAIN MENU Option D : Search Chart Menu
#m3.3.5#m SPC MAIN MENU Option E : View Patterns Menu
#m3.3.6#m SPC MAIN MENU Option F : Consultation Menu
#m3.3.7#m SPC MAIN MENU Option G : More Information
#m3.3.8#m SPC MAIN MENU Option H : Print Menu
#m3.3.9#m SPC MAIN MENU Option I : Options Menu
#m3.3.10#m SPC MAIN MENU Option J : Editor/File Manager
#m3.3.11#m SPC MAIN MENU Final Option : quit
#m3.4#m Raw Data File Formats
#m3.4.1#m RUN Chart Raw Data File Format
#m3.4.2#m XMR (Moving Range) Chart Raw Data File Format
#m3.4.3#m XBAR-R Chart Raw Data File Format
#m3.4.4#m XBAR-S Chart Raw Data File Format
#m3.4.5#m PN Chart Raw Data File Format
#m3.4.6#m P Chart Raw Data File Format
#m3.4.7#m C Chart Raw Data File Format
#m3.4.8#m U Chart Raw Data File Format
#m3.4.9#m Bar Graph Raw Data File Format
#m3.4.10#m Pareto Chart Raw Data File Format
#m3.4.11#m Pie Chart Raw Data File Format
#m3.4.12#m Histogram Raw Data File Format
#m3.4.13#m Frequency Polygon Raw Data File Format
#m3.4.14#m Ogive (CDF) Raw Data File Format
#m3.4.15#m Scatter Diagram Raw Data File Format
#m4#m. POINTS OF CONTACT
#m5#m. REFERENCES
OVERVIEW
The Special Projects Office of the Center for Supportability and
Technology Insertion (CSTI) has developed a software tool which
automates the statistical and graphical tools used in Statistical
Quality Control and process metrics analysis. These tools include:
Run Chart P Chart Pie Chart
Moving Range Chart C Chart Histogram
XBar-R Chart U Chart Frequency Polygon
XBar-S Chart Bar Graph Ogive (CDF)
PN Chart Pareto Diagram Scatter Diagram
SPC Version 1.1 is available FREE to all government agencies.
Since this is government owned and developed software, government
agencies are free to duplicate the software and documentation as
needed. However, in order to keep in contact with our customers
and provide them the opportunity to obtain the most recent versions
of the SPC software tool, we need to know who is using the software
and what their needs are. For these reasons, the following items
are included on the next two pages:
1. Software request forms for SPC Version 1.1. Provide copies
of these to individuals who are interested in receiving a copy
of SPC Version 1.1.
2. User registration forms. Complete and return this form to
register as an SPC user. This will automatically register you
to receive SPC Version 1.2 tentatively scheduled for release
in September 1992. ONLY REGISTERED USERS WILL AUTOMATICALLY
RECEIVE THE NEXT VERSION OF THE SOFTWARE! This form also
provides you the opportunity to join the SPC User's Group.
CSTI will regularily poll the user's group as one of the
primary sources of requirements for enhancements to the
software. THIS IS THE OPPORTUNITY FOR YOU TO DIRECTLY IMPACT
THE CONTENTS OF FUTURE SOFTWARE RELEASES!
1. INTRODUCTION
The Air Force Logistics Command (AFLC) has provided Total Quality
Management (TQM) and Quality Control (QC) training to its employees
for several years now. In particular, Statistical Process Control
has been emphasized in this effort. While many data collection and
process improvement efforts have been undertaken within AFLC, the
SPC Quality Control tool has been under-utilized due to the
difficulty of manual application of these techniques. In response,
CSTI has developed a software tool (SPC) which automates the
statistical and graphical tools used in Statistical Quality
Control. SPC draws control charts, identifies various chart
patterns, advises what each pattern means, and suggests possible
corrective actions. The application is easily modifiable for
process specific applications through simple modifications to the
knowledge base portion using any word processing software. SPC
also constructs bar graphs, pareto charts, pie charts, histograms,
frequency polygons, ogives (cummulative distribution functions) and
scatter diagrams and in addition provides correlation analysis for
the scatter diagrams.
1.1 Bar Graphs
Bar Graphs are a very simple way of illustrating the nature of your
process data. A bar graph simply illustrates the relative
frequencies or magnitude of data which can be broken down into
distinct categories.
1.2 Pareto Charts
There are many aspects of any process that could be improved :
defectives, time allocation, cost savings, rework, etc. In fact,
each problem consists of so many smaller problems that it is
difficult to know just where to begin solving them. In order to be
efficient, a definite basis is needed for any action.
A Pareto chart is the tool to use when you need to display the
relative importance of all of the problems or conditions in order
to : choose the starting point for problem solving, monitor
success, or identify the basic cause of a problem.
A Pareto Chart is a special form of a vertical bar graph which
helps us determine which problems to solve in what order. Doing a
Pareto Chart based upon either Check Sheets or other forms of data
collection helps us direct our attention and efforts to the truly
important problems. We will generally gain more by working on the
tallest bar than tackling the smaller bars. More information
concerning the use of Pareto Charts is available through SPC's
MORE INFORMATION MENU.
1.3 Pie Charts
Pie Charts are simply graphs in which the entire circle represents
100% (not 360 degrees) of the data to be displayed. The circle
(pie) is divided into percentage slices that clearly show the
largest shares of data. This is useful in the same was a a Pareto
Chart. The Pie Chart is sometimes even more useful since it is
widely used to display data on T.V. or in the newspapers. More
information concerning the use of Pareto Charts is available
through SPC's MORE INFORMATION MENU.
1.4 Scatter Diagrams
A Scatter Diagram is the tool to use when you need to display what
happens to one variable when another variable changes in order to
test a theory that the two variables are related.
A Scatter Diagram is used to study the possible relationship
between one variable and another. The Scatter Diagram is used to
test for possible cause and effect relationships. It cannot prove
that one variable causes the other, but it does make it clear
whether a relationship exists and the strength of that
relationship.
A Scatter Diagram is set up whereby the horizontal axis (x-axis)
represents the measurement values of one variable, and the vertical
axis (y-axis) represents the measurement values of the second
variable. More information concerning the use of Scatter Diagrams
is available through SPC's MORE INFORMATION MENU.
1.5 Histograms
As we have already seen with the Pareto Chart, it is very helpful
to display in bar graph form the frequency with which certain
events occur (frequency distribution). The Pareto Chart, however,
only deals with characteristics of a product or service, e.g., type
of defect, problem, saftey hazards, etc. (attribute data). A
Histogram takes measurement data, e.g., temperature, dimensions,
etc., and displays it's distribution. This is critical since we
know that all repeated events will produce results that vary over
time. A Histogram reveals the amount of variation that any process
has within it.
1.6 Frequency Polygons
Another kind of graphical display of a frequency distribution
(Histogram) is the Frequency Polygon. Here the cell (data range)
frequencies are plotted at the midpoint of each cell and the
midpoints are joined by straight lines.
1.7 Ogives (Cummulative Distribution Function)
If the same technique in the Frequency Polygon is applied to the
cummulative distribution function, we obtain what is called an
Ogive (rhymes with alive) or CDF. The only difference is that in
constructing the Ogive (CDF), the cell boundary is used as the plot
point rather than the middle of the cell.
1.8 Control Charts
A run chart is a plot of a process measurement (e.g. bore diameter
or time to process an insurance claim for example) on the vertical
axis (y-axis) against time on the horizontal axis (x-axis). A
control chart is simply a run chart with statistically determined
upper (Upper Control Limit - UCL) and lower (Lower Control Limit -
LCL) lines drawn on either side of the process average. These
limits are calculated by running a process untouched, taking
samples of the process measurement, and applying the appropriate
statistical formulas (references [3-9]).
The random fluctuation of points within the limits results from
variation built into the process. Such random variation is
natural, results from common causes within the system (e.g. design,
choice of machine, preventative maintenance, etc.), and can only be
affected by changing the system itself. However, points which fall
outside of the control limits or which form "unnatural" patterns
indicate that some of the variation within the process may be due
to assignable causes. Assignable causes of variation (e.g.
measurement errors, unplanned events, freak occurrences, etc.) can
be identified and result from occurrences that are not part of the
process.
The purpose of drawing the control chart is to detect any unusual
causes of variation in the process, signalled by abnormal points or
patterns on the graph. The CSTI developed software tool
automatically identifies nine types of patterns which indicate the
presence of assignable causes of variation in a process. Each such
pattern is associated with generic advice about what may be happening
at that point in the process.
1.9 Software Functionality
An overview of the functionality of SPC is given below :
1.9.1 Control Charts
(1) SPC determines which type of control chart is appropriate
by asking a series of questions about the nature of the user's
process data. The appropriate control chart is selected from
the following types of charts (See References [3,4,5,6]) :
(a) Run Chart
(b) Moving Range Chart (XMR)
(c) X-Bar R Chart
(d) X-Bar S Chart
(e) p Chart
(f) pn Chart
(g) u Chart
(h) c Chart
(2) SPC graphically displays the chart(s) selected in (1).
(3) SPC identifies the following patterns in the chart(s)
which indicate the presence of assignable causes of variation:
(a) increasing trends
(b) decreasing trends
(c) shifts up
(d) shifts down
(e) cycles
(f) runs
(g) stratification
(h) freak patterns
(i) freak points
(4) SPC graphically displays and highlights each chart pattern
identified in (3).
(5) SPC displays text in a hypertext fashion which provides
generic advice on the meaning of each chart pattern identified
in (3).
(6) SPC provides regression analysis for run charts.
1.9.2 Other Diagrams and Graphs
(1) SPC will display the following Diagrams/Graphs constructed
from user-provided data :
(a) Bar Graphs
(b) Pareto Diagrams
(c) Pie Charts
(d) Histograms
(e) Frequency Polygons
(f) Ogive (CDF)
(g) Scatter Diagrams
(2) SPC provides correlation and regression analysis for
scatter diagrams.
1.10 Unique Features of SPC
Four features distinguish SPC from most other control chart
software :
(1) SPC is FREE to all government agencies.
(2) SPC is extremely user-friendly even for non-statisticians.
(3) SPC automatically identifies and highlights unusual
control chart patterns. Most related commercial software will
simply draw the chart and explain to the user what unusual
patterns to look for.
(4) SPC provides expert advice on the meaning of all
identified unusual control chart patterns.
1.11 SPC Software Support
SPC Version 1.1 is scheduled to be available by March 1992. CSTI
plans to provide software enhancements to SPC based upon customer
feedback and demand. SPC Version 1.2 is tentatively scheduled to
be released in September 1992. A Beta-test version of SPC 1.1 for
the PC LAN (SPC PC-LAN Version 1.1B) is scheduled for limited field
testing in June 1992. Additional copies of SPC are available FREE
to government agencies upon request. Domestic companies and U.S.
citizens may obtain copies of SPC Version 1.1 via written request.
2. INSTALLATION
The Statistical Process Control Chart Interpretation System (SPC)
requires an IBM PC AT or compatible with a hard disk drive (1M free
disk space) to execute. While SPC uses a mouse, one is not
required to operate the program. To install the software simply
copy the entire contents of the SPC System Diskette into a separate
sub-directory (c:\spc for the example below) on your hard disk and
execute the installation routine "spcinst". This can be
accomplished with the following steps :
(a) Place the SPC System Diskette into the a: drive.
(b) Type "c:"<ENTER>
(c) Type "md c:\spc"<ENTER>
(d) Type "cd c:\spc"<ENTER>
(e) Type "copy a:*.*"<ENTER>
(f) Type "spcinst" <ENTER>
When complete, the SPC installation routine (step f above) will
display the message "SPC Version 1.1 INSTALLED".
3. EXECUTION
This section outlines the steps required to execute both the
demonstration program (spcdemo.bat) and the SPC software
(cspc.exe).
3.1 Executing Demonstration Program
The demonstration program provides you with a menu of options. The
first 15 options labeled A - O allow you to enter the SPC tool with
predefined and pre-searched data sets. The 16th option (P) allows
you to enter the SPC tool itself. The 17th option (Q) will run a
program which displays examples of all the charts and graphs
available. To exit out of the repeating graphics screens, hit any
non-numeric key. The numeric keys 1-9 adjust the time that each
graphic is displayed before the next appears.
To start the demonstration program :
(a) Type "c:" <ENTER>
(b) Type "cd c:\spc"<ENTER>
(c) Type "spcdemo"<ENTER>
After step (c), the SPC DEMONSTRATION MENU will appear as
illustrated below.
SPC DEMONSTRATION MENU
A. Sample Run Chart
B. Sample Moving Range Chart
C. Sample Xbar-R Chart
D. Sample Xbar-S Chart
E. Sample P Chart
F. Sample PN Chart
G. Sample C Chart
H. Sample U Chart
I. Sample Bar Chart
J. Sample Pareto Diagram
K. Pie Chart
L. Scatter Diagram
M. Histogram (Frequency Dist)
N. Frequency Polygon
O. Ogive (CDF)
P. SPC Tool
Q. Display Demo
exit demonstration
You are encouraged to try the demonstration program first before
using your own data sets. To use the SPC DEMONSTRATION MENU,
simply move the selection bar over the desired data set using the
arrow keys on your keyboard. To select an option, press <ENTER> or
<RETURN>. After viewing several sample data sets, you should be
ready to use SPC with your own data (Section 3.2).
3.2 Executing SPC Chart Interpretation System Software
To start the SPC program :
(a) Type "c:" <ENTER>
(b) Type "cd c:\spc"<ENTER>
(c) Type "cspc"<ENTER>
3.3 SPC MAIN MENU and STATUS BOX
When you execute SPC, the SPC MAIN MENU and STATUS BOX will appear
on the screen. This is the primary screen from which you will
utilize SPC. The SPC MAIN MENU contains 11 selections listed
below:
CURRENT STATUS
-------------------------------------------------
Raw Data File rand.gph
Chart Type XBAR_R
Valid Chart? Yes
Pattern Search Complete (Long)
Patterns 4
SPC MAIN MENU
A. Select Raw Data File
B. Select Chart/Diagram Type
C. View Chart/Diagram
D. Search Control Chart Menu
E. View Chart Patterns Menu
F. Expert Consultation Menu
G. More Information
H. Print Menu
I. Options
J. SPC Editor & File Manager
quit
The SPC STATUS BOX provides a summary of the results of previous
SPC MAIN MENU selections.
3.3.1 SPC MAIN MENU Option A : Select Raw Data File
Option A allows you to enter the name of the ASCII file which
contains your raw process data. See Section 3.4 for raw process
data file formats. You must create a raw data file BEFORE viewing
a graph or diagram. Several sample raw data files are included on
the SPC System Disk. The names of these files are listed below.
<filename> <chart-type>
#trun.gph#t RUN
#txmr.gph#t XMR
#tinbox.gph#t XBAR-R
#txs.gph#t XBAR-S
#tpntest.gph#t PN
#tptest.gph#t P
#tctest.gph#t C
#tutest.gph#t U
#tdivision.bar#t BAR/PARETO/PIE
#tweight.sct#t SCATTER
#tpositive.sct#t SCATTER
#tnegative.sct#t SCATTER
#thist.dat#t HISTOGRAM/CDF/POLYGON
3.3.2 SPC MAIN MENU Option B : Select Chart/Diagram Type
Option B allows you to directly select the type of control chart or
diagram that is appropriate. An automatic selection option is also
available which will make this determination for control charts
based upon the nature of your process data. When Option B is
selected, the CHART TYPE MENU will be displayed. The selections in
the CHART TYPE MENU are listed below. Either the SPC CONTROL CHART
TYPE MENU or the SPC DIAGRAM/GRAPH TYPE MENU will appear depending
upon your selection from the SPC CHART TYPE MENU.
CHART TYPE MENU
A. Control charts
B. Diagrams and Graphs
C. Return to SPC MAIN MENU
CONTROL CHART TYPE MENU
A. Automatic chart selection
B. Run chart
C. Moving Range control chart
D. Xbar-R control chart
E. Xbar-S control chart
F. pn control chart
G. p control chart
H. c control chart
I. u control chart
J. Return to SPC Main Menu
GRAPH/DIAGRAM TYPE MENU
A. Bar Graph
B. Pareto Diagram
C. Scatter Diagram
D. Histogram
E. Frequency Polygon
F. CDF or Ogive
G. Pie Chart
H. Return to SPC MAIN MENU
3.3.3 SPC MAIN MENU Option C : View Chart/Diagram
Option C allows you to view a graphic display of your control chart
or diagram.
3.3.4 SPC MAIN MENU Option D : Search Chart Patterns Menu
Option D is used to search your control chart for unusual patterns.
When you select option D, the menu to the right appears :
Documentation detailing each of these options is available by
either pressing <F1> when the menu appears or by using SPC MAIN
MENU option G (More Information) followed by option 5 (Search Chart
Patterns Menu) from the MORE INFORMATION MENU.
1. Short Search
2. Long Search
3. Retrieve Patterns From File
4. Save Current Patterns To File
5. View List of Current Patterns
6. Return To SPC Main Menu
Option D is not available for Bar Graphs, Pareto Charts, Pie
Charts, Histograms, Frequency Polygons, Ogives (CDFs), or
Scatter Diagrams.
3.3.5 SPC MAIN MENU Option E : View Patterns Menu
Option E allows you to view any unusual patterns found during the
pattern search in Option D. The patterns appear highlighted on the
graphic display of your control chart. You have the option to view
the patterns individually or all together.
Option E is not available for Bar Graphs, Pareto Charts, Pie
Charts, Histograms, Frequency Polygons, Ogives (CDFs), or
Scatter Diagrams.
3.3.6 SPC MAIN MENU Option F : Expert Consultation Menu
Option F allows you to view expert advice concerning the meaning of
any unusual patterns found in your chart (Option D). You have the
option to view advice for individual patterns or for all of the
patterns.
Option F is not available for Bar Graphs, Pareto Charts, Pie
Charts, Histograms, Frequency Polygons, Ogives (CDFs), or
Scatter Diagrams.
3.3.7 SPC MAIN MENU Option G : More Information
Option G provides on-line documentation about SPC. When Option G
is selected, the following menu will come up :
Each selection in the SPC MORE INFORMATION MENU displays several
pages of text relating to that particular subject or software
feature.
3.3.8 SPC MAIN MENU Option H : Print Menu
Option H allows you to make a paper print-out of the current chart
or diagram. More detailed help is available by pressing <F1> at
any of the printer option menus.
SPC Version 1.1 supports the following printers :
A. Epson FX/IBM Pro Printer
B. Epson LQ
C. IBM Proprinter X24
D. IBM Quietwriter
E. Toshiba P321
F. HP Laserjet/Desk Jet
G. Post Script Monochrome
H. Post Script Grayscale
I. Post Script Color
SPC Version 1.1 supports the following print orientations :
A. Half-Page
B. Land-Scape
C. Full-Page
SPC Version 1.1 supports the following print densities :
A. 75 dpi (Draft)
B. 150 dpi (Medium)
C. 300 dpi (High)
SPC Version 1.1 supports the following printer ports :
A. LPT1 (Parallel Port #1)
B. LPT2 (Parallel Port #2)
C. COM1 (Serial Port #1)
D. COM2 (Serial Port #2)
3.3.9 SPC MAIN MENU Option I : Options Menu
OPTION I HAS NOT BEEN FULLY DEVELOPED YET. Many of the items in
the OPTIONS MENU have been disabled (i.e. you cannot select them).
However, some of the options are available. These options allow
you to set various parameters which affect the performance/output
of SPC such as:
(a) Set Titles Font and Font Size
(b) Set Control Limit Type (Run charts Only)
(c) Set/Display Upper/Lower Spec. Limits (Run Only)
(d) Turn Regression Line ON/OFF (Run & Scatter Only)
(e) Turn Sound ON/OFF
(f) Display FIle Info In Graphics ON/OFF
Remember, this option is still experimental for SPC Version 1.1.
3.3.10 SPC MAIN MENU Option J : SPC Editor/File Manager
Option J allows you to edit any ASCII text file that is in the SPC
directory on your computer. You may directly edit the current raw
data file by selecting Option 1 from the SPC EDITOR MENU. If you
would like to create or edit any other ASCII text file, select
option 2 from the SPC EDIT MENU. You will then be prompted for the
name of the file you wish to edit. The SPC File Manager also
allows you to view, copy, rename, or delete any files. Detailed
help on using the SPC Editor is available from within the editor by
pressing <F1>.
3.3.11 SPC MAIN MENU Final Option : quit
Use the last Option to exit the SPC application.
3.4. Raw Data File Formats.
SPC will generate 8 different types of control charts -
RUN,XMR,XBAR-R,XBAR-S,PN,P,C,U and 7 diagrams - BAR, PARETO, PIE,
HISTOGRAM, Frequency POLYGON, Ogive (CDF), and SCATTER. Each type
of control chart or diagram requires a slightly different format
for the ASCII file which contains the raw process data. For all
types of charts and diagrams, entries in the raw data file must be
separated by spaces or returns. DO NOT SEPARATE ENTRIES WITH
COMMAS, ETC! The appropriate formats are outlined below.
THE FIRST FOUR LINES OF EVERY RAW DATA FILE CONTAINS THE SAME
TYPE OF INFORMATION :
Line 1 : Title
Line 2 : Subtitle
Line 3 : X (Horizontal) Axis-Label
Line 4 : Y (Vertical) Axis Label
Lines 1-4 of each raw data file may be any string of numbers
or characters you desire. The length of each line may be
anywhere from 0 characters up to 80 characters followed by a
carriage return.
3.4.1 RUN Chart Raw Data File Format
The first four lines contain title and axis label information. All
remaining entries in a RUN Chart must be numeric. The length of
the chart will be the number of entries after the first four lines.
SPC limits the number of entries in a RUN Chart to 100 or less. A
sample RUN Chart raw data file is located in the file "#trun.gph#t" on
your SPC System Disk.
3.4.2 XMR (Moving Range) Chart Raw Data File Format
The format for an XMR (Moving Range) Control Chart is identical to
the required format for the RUN Chart given in 3.4.1.
3.4.3 XBAR-R Chart Raw Data File Format
The first four lines contain title and axis label information. The
next entry (line 5) is an INTEGER between 1 and 10 inclusive. This
number represents the logical group size or sample size. The
remaining entries (REAL or INTEGER) represent the actual process
measurements. The length of the chart(s) will be the number of
process measurements divided by the logical group size. For
example, if we have a group size of 3 and 69 process measurements,
then the length of the XBAR and R Charts will be 23. Sample XBAR-R
raw data files are located in files "#tinbox.gph#t" and "#trand.gph#t" on
your SPC System Disk.
3.4.4 XBAR-S Chart Raw Data File Format
The format for an XBAR-S Control Chart is identical to the required
format for the XBAR-R Control Chart except that the logical group
(sample) size must be between 3 and 50. The raw data file format
for the XBar-R chart is given in 3.4.3.
3.4.5 PN Chart Raw Data File Format
The first four lines contain title and axis label information. All
remaining entries in a PN Chart raw data file must be INTEGERS.
The first entry represents the fixed sample size. The remaining
entries represent the number of defectives (rejects/failures) out
of the fixed number of samples. The length of the PN chart will be
one less than the number of entries in the raw data file. A sample
PN raw data file is located in the file "#tpntest.gph#t".
3.4.6 P Chart Raw Data File Format
The first four lines contain title and axis label information. All
remaining entries in a P Chart raw data file must be PAIRS of
INTEGERS. The first integer in each pair represents the sample
size and the second integer represents the number of defectives or
rejects. The length of the P Chart will be the number of pairs of
entries. A sample P raw data file is located in the file
"#tptest.gph#t".
3.4.7 C Chart Raw Data File Format
The first four lines contain title and axis label information. All
remaining entries in a C Chart raw data file must be INTEGERS.
Each entry represents the number of defects (errors) in a sample of
fixed size/weight/length/etc. The length of the C chart will be
the number of entries in the raw data file. A sample C raw data
file is located in the file "#tctest.gph#t".
3.4.8 U Chart Raw Data File Format
The first four lines contain title and axis label information. All
remaining entries in a U Chart must be PAIRS of entries. The first
entry in each pair can be either INTEGER or REAL and represents the
sample size/length/weight/etc. The second entry must be an INTEGER
and represents the number of defects/errors/etc. in the sample.
The length of the U Chart will be the number of pairs of entries.
A sample U raw data file is located in the file "#tutest.gph#t".
3.4.9 Bar Graph Raw Data File Format
The first four lines contain title and axis label information. The
numeric data consists of PAIRS of entries. The first entry in each
pair can be any non-negative number, INTEGER or REAL. The second
entry in each pair can be anything - this will be the
classification name for the category that this pair represents. A
Bar Graph is limited to 20 pairs of entries. Sample Bar Graph Raw
data files are located in files "#tdivision.bar#t" and "#tsample.bar#t".
3.4.10 Pareto Chart Raw Data File Format
The format for a Pareto Diagram raw data file is identical to the
required format for the Bar Graph given in 3.4.9.
3.4.11 Pie Chart Raw Data File Format
The format for a PIE Chart raw data file is identical to the
required format for the Bar Graph given in 3.4.9.
3.4.12 Histogram Raw Data File Format
The first four lines contain title and axis label information. The
numeric data consists of numeric entries. Each entry can be any
number, INTEGER or REAL. A Histogram is limited to 500 numeric
entries. Sample Histogram Raw data files are located in files
"#thist.dat#t" and "#tsample.dat#t".
3.4.13 Frequency Polygon Raw Data File Format
The format for a Frequency Polygon raw data file is identical to
the required format for the Histogram given in 3.4.12.
3.4.14 Ogive (CDF) Raw Data File Format
The format for a CDF raw data file is identical to the required
format for the Histogram given in 3.4.12.
3.4.15 Scatter Diagram Raw Data File Format
The first four lines contain title and axis label information. The
numeric data consists of PAIRS of entries. Both entries in each
pair can be any number, INTEGER or REAL. The first number in each
pair will be displayed on the horizontal axis (x-axis) and the
second on the vertical axis (y-axis). A scatter diagram is limited
to 200 pairs of entries. Sample Scatter Diagram raw data files are
located in files "#tpositive.sct#t", "#tnegative.sct#t", and "#trandom.sct#t".
4. POINTS OF CONTACT
If you have questions or comments concerning the SPC software,
please feel free to contact Mark Shewhart at DSN : 785-7003 or COM
: (513) 255-7003.
5. REFERENCES
[1] Spyros Makridakis and Stephen C. Wheelwright, "Forecasting:
Methods and Applications",Wiley/Hamilton, 1978.
[2] Sir Maurice Kendall and J Keith Ord, "Time Series", Oxford
University Press, 1990.
[3] SPC Course Materials, Decision Dynamics Inc., 1990
[4] Kaoru Ishikawa, "Guide to Quality Control", Asian Productivity
Organization, 1982.
[5] Perry Johnson Inc., "SPC Chart Interpretation", Perry Johnson,
Inc., 1987.
[6] J.M. Juran, Dr. Frank M. Gryna, Jr., and R.S. Bingham, Jr.,
"Quality Control Handbook",Third Edition, McGraw-Hill, 1974.
[7] Western Electric Company, "Statistical Quality Control
Handbook", Western Ellectric Co., Inc., 1958.
[8] H. Besterfield, "Quality Control", Second Edition, Prentice-
Hall.
[9] Douglas C. Montogomery, "Introduction to Statistical Quality
Control".
[10] Mark Shewhart, "Application of Machine Learning and Expert
Systems to Statistical Process Control Chart Interpretation", 2nd
Annual CLIPS Conference Proceedings (1991).
[11] "The Memory Jogger : A Pocket Guide of Tools For Continuous
Improvement", GOAL/QPC, 1988.
[12] Kiemele & Schmidt, "Basic Statistics : Tools for Continuous
Improvement", Air Academy Press, Second Edition 1991.
@
0
OVERVIEW
The Special Projects Office of the Center for Supportability and
Technology Insertion (CSTI) has developed a software tool which
automates the statistical and graphical tools used in Statistical
Quality Control and process metrics analysis. These tools include:
Run Chart P Chart Pie Chart
Moving Range Chart C Chart Histogram
XBar-R Chart U Chart Frequency Polygon
XBar-S Chart Bar Graph Ogive (CDF)
PN Chart Pareto Diagram Scatter Diagram
SPC Version 1.1 is available FREE to all government agencies.
Since this is government owned and developed software, government
agencies are free to duplicate the software and documentation as
needed. However, in order to keep in contact with our customers
and provide them the opportunity to obtain the most recent versions
of the SPC software tool, we need to know who is using the software
and what their needs are. For these reasons, the following items
are included on the next two pages:
1. Software request forms for SPC Version 1.1. Provide copies
of these to individuals who are interested in receiving a copy
of SPC Version 1.1.
2. User registration forms. Complete and return this form to
register as an SPC user. This will automatically register you
to receive SPC Version 1.2 tentatively scheduled for release
in September 1992. ONLY REGISTERED USERS WILL AUTOMATICALLY
RECEIVE THE NEXT VERSION OF THE SOFTWARE! This form also
provides you the opportunity to join the SPC User's Group.
CSTI will regularily poll the user's group as one of the
primary sources of requirements for enhancements to the
software. THIS IS THE OPPORTUNITY FOR YOU TO DIRECTLY IMPACT
THE CONTENTS OF FUTURE SOFTWARE RELEASES!
@
1
1. INTRODUCTION
The Air Force Logistics Command (AFLC) has provided Total Quality
Management (TQM) and Quality Control (QC) training to its employees
for several years now. In particular, Statistical Process Control
has been emphasized in this effort. While many data collection and
process improvement efforts have been undertaken within AFLC, the
SPC Quality Control tool has been under-utilized due to the
difficulty of manual application of these techniques. In response,
CSTI has developed a software tool (SPC) which automates the
statistical and graphical tools used in Statistical Quality
Control. SPC draws control charts, identifies various chart
patterns, advises what each pattern means, and suggests possible
corrective actions. The application is easily modifiable for
process specific applications through simple modifications to the
knowledge base portion using any word processing software. SPC
also constructs bar graphs, pareto charts, pie charts, histograms,
frequency polygons, ogives (cummulative distribution functions) and
scatter diagrams and in addition provides correlation analysis for
the scatter diagrams.
@
1.1
1.1 Bar Graphs
Bar Graphs are a very simple way of illustrating the nature of your
process data. A bar graph simply illustrates the relative
frequencies or magnitude of data which can be broken down into
distinct categories.
@
1.2
1.2 Pareto Charts
There are many aspects of any process that could be improved :
defectives, time allocation, cost savings, rework, etc. In fact,
each problem consists of so many smaller problems that it is
difficult to know just where to begin solving them. In order to be
efficient, a definite basis is needed for any action.
A Pareto chart is the tool to use when you need to display the
relative importance of all of the problems or conditions in order
to : choose the starting point for problem solving, monitor
success, or identify the basic cause of a problem.
A Pareto Chart is a special form of a vertical bar graph which
helps us determine which problems to solve in what order. Doing a
Pareto Chart based upon either Check Sheets or other forms of data
collection helps us direct our attention and efforts to the truly
important problems. We will generally gain more by working on the
tallest bar than tackling the smaller bars. More information
concerning the use of Pareto Charts is available through SPC's
MORE INFORMATION MENU.
@
1.3
1.3 Pie Charts
Pie Charts are simply graphs in which the entire circle represents
100% (not 360 degrees) of the data to be displayed. The circle
(pie) is divided into percentage slices that clearly show the
largest shares of data. This is useful in the same was a a Pareto
Chart. The Pie Chart is sometimes even more useful since it is
widely used to display data on T.V. or in the newspapers. More
information concerning the use of Pareto Charts is available through
SPC's MORE INFORMATION MENU.
@
1.4
1.4 Scatter Diagrams
A Scatter Diagram is the tool to use when you need to display what
happens to one variable when another variable changes in order to
test a theory that the two variables are related.
A Scatter Diagram is used to study the possible relationship
between one variable and another. The Scatter Diagram is used to
test for possible cause and effect relationships. It cannot prove
that one variable causes the other, but it does make it clear
whether a relationship exists and the strength of that
relationship.
A Scatter Diagram is set up whereby the horizontal axis (x-axis)
represents the measurement values of one variable, and the vertical
axis (y-axis) represents the measurement values of the second
variable. More information concerning the use of Scatter Diagrams
is available through SPC's MORE INFORMATION MENU.
@
1.5
1.5 Histograms
As we have already seen with the Pareto Chart, it is very helpful
to display in bar graph form the frequency with which certain
events occur (frequency distribution). The Pareto Chart, however,
only deals with characteristics of a product or service, e.g., type
of defect, problem, saftey hazards, etc. (attribute data). A
Histogram takes measurement data, e.g., temperature, dimensions,
etc., and displays it's distribution. This is critical since we
know that all repeated events will produce results that vary over
time. A Histogram reveals the amount of variation that any process
has within it.
@
1.6
1.6 Frequency Polygons
Another kind of graphical display of a frequency distribution
(Histogram) is the Frequency Polygon. Here the cell (data range)
frequencies are plotted at the midpoint of each cell and the
midpoints are joined by straight lines.
@
1.7
1.7 Ogives (Cummulative Distribution Function)
If the same technique in the Frequency Polygon is applied to the
cummulative distribution function, we obtain what is called an
Ogive (rhymes with alive) or CDF. The only difference is that in
constructing the Ogive (CDF), the cell boundary is used as the plot
point rather than the middle of the cell.
@
1.8
1.8 Control Charts
A run chart is a plot of a process measurement (e.g. bore diameter
or time to process an insurance claim for example) on the vertical
axis (y-axis) against time on the horizontal axis (x-axis). A
control chart is simply a run chart with statistically determined
upper (Upper Control Limit - UCL) and lower (Lower Control Limit -
LCL) lines drawn on either side of the process average. These
limits are calculated by running a process untouched, taking
samples of the process measurement, and applying the appropriate
statistical formulas (references [3-9]).
The random fluctuation of points within the limits results from
variation built into the process. Such random variation is
natural, results from common causes within the system (e.g. design,
choice of machine, preventative maintenance, etc.), and can only be
affected by changing the system itself. However, points which fall
outside of the control limits or which form "unnatural" patterns
indicate that some of the variation within the process may be due
to assignable causes. Assignable causes of variation (e.g.
measurement errors, unplanned events, freak occurrences, etc.) can
be identified and result from occurrences that are not part of the
process.
The purpose of drawing the control chart is to detect any unusual
causes of variation in the process, signalled by abnormal points or
patterns on the graph. The CSTI developed software tool
automatically identifies nine types of patterns which indicate the
presence of assignable causes of variation in a process. Each such
pattern is associated with generic advice about what may be happening
at that point in the process.
@
1.9
1.9 Software Functionality
An overview of the functionality of SPC is given below :
@
1.9.1
1.9.1 Control Charts
(1) SPC determines which type of control chart is appropriate
by asking a series of questions about the nature of the user's
process data. The appropriate control chart is selected from
the following types of charts (See References [3,4,5,6]) :
(a) Run Chart
(b) Moving Range Chart (XMR)
(c) X-Bar R Chart
(d) X-Bar S Chart
(e) p Chart
(f) pn Chart
(g) u Chart
(h) c Chart
(2) SPC graphically displays the chart(s) selected in (1).
(3) SPC identifies the following patterns in the chart(s)
which indicate the presence of assignable causes of variation
:
(a) increasing trends
(b) decreasing trends
(c) shifts up
(d) shifts down
(e) cycles
(f) runs
(g) stratification
(h) freak patterns
(i) freak points
(4) SPC graphically displays and highlights each chart pattern
identified in (3).
(5) SPC displays text in a hypertext fashion which provides
generic advice on the meaning of each chart pattern identified
in (3).
(6) SPC provides regression analysis for run charts.
@
1.9.2
1.9.2 Other Diagrams and Graphs
(1) SPC will display the following Diagrams/Graphs constructed
from user-provided data :
(a) Bar Graphs
(b) Pareto Diagrams
(c) Pie Charts
(d) Histograms
(e) Frequency Polygons
(f) Ogive (CDF)
(g) Scatter Diagrams
(2) SPC provides correlation and regression analysis for
scatter diagrams.
@
1.10
1.10 Unique Features of SPC
Four features distinguish SPC from most other control chart
software :
(1) SPC is FREE to all government agencies.
(2) SPC is extremely user-friendly even for non-statisticians.
(3) SPC automatically identifies and highlights unusual
control chart patterns. Most related commercial software will
simply draw the chart and explain to the user what unusual
patterns to look for.
(4) SPC provides expert advice on the meaning of all
identified unusual control chart patterns.
@
1.11
1.11 SPC Software Support
SPC Version 1.1 is scheduled to be available by March 1992. CSTI
plans to provide software enhancements to SPC based upon customer
feedback and demand. SPC Version 1.2 is tentatively scheduled to
be released in September 1992. A Beta-test version of SPC 1.1 for
the PC LAN (SPC PC-LAN Version 1.1B) is scheduled for limited field
testing in June 1992. Additional copies of SPC are available FREE
to government agencies upon request. Domestic companies and U.S.
citizens may obtain copies of SPC Version 1.1 via written request.
@
2
2. INSTALLATION
The Statistical Process Control Chart Interpretation System (SPC)
requires an IBM PC AT or compatible with a hard disk drive (1M free
disk space) to execute. While SPC uses a mouse, one is not
required to operate the program. To install the software simply
copy the entire contents of the SPC System Diskette into a separate
sub-directory (c:\spc for the example below) on your hard disk and
execute the installation routine "spcinst". This can be
accomplished with the following steps :
(a) Place the SPC System Diskette into the a: drive.
(b) Type "c:"<ENTER>
(c) Type "md c:\spc"<ENTER>
(d) Type "cd c:\spc"<ENTER>
(e) Type "copy a:*.*"<ENTER>
(f) Type "spcinst" <ENTER>
When complete, the SPC installation routine (step f above) will
display the message "SPC Version 1.1 INSTALLED".
@
3
3. EXECUTION
This section outlines the steps required to execute both the
demonstration program (spcdemo.bat) and the SPC software
(cspc.exe).
@
3.1
3.1 Executing Demonstration Program
The demonstration program provides you with a menu of options. The
first 15 options labeled A - O allow you to enter the SPC tool with
predefined and pre-searched data sets. The 16th option (P) allows
you to enter the SPC tool itself. The 17th option (Q) will run a
program which displays examples of all the charts and graphs
available. To exit out of the repeating graphics screens, hit any
non-numeric key. The numeric keys 1-9 adjust the time that each
graphic is displayed before the next appears.
To start the demonstration program :
(a) Type "c:" <ENTER>
(b) Type "cd c:\spc"<ENTER>
(c) Type "spcdemo"<ENTER>
After step (c), the SPC DEMONSTRATION MENU will appear as
illustrated below.
A. Sample Run Chart
B. Sample Moving Range Chart
C. Sample Xbar-R Chart
D. Sample Xbar-S Chart
E. Sample P Chart
F. Sample PN Chart
G. Sample C Chart
H. Sample U Chart
I. Sample Bar Chart
J. Sample Pareto Diagram
K. Pie Chart
L. Scatter Diagram
M. Histogram (Frequency Dist)
N. Frequency Polygon
O. Ogive (CDF)
P. SPC Tool
Q. Display Demo
exit demonstration
You are encouraged to try the demonstration program first before
using your own data sets. To use the SPC DEMONSTRATION MENU,
simply move the selection bar over the desired data set using the
arrow keys on your keyboard. To select an option, press <ENTER> or
<RETURN>. After viewing several sample data sets, you should be
ready to use SPC with your own data (Section 3.2).
@
3.2
3.2 Executing SPC Chart Interpretation System Software
To start the SPC program :
(a) Type "c:" <ENTER>
(b) Type "cd c:\spc"<ENTER>
(c) Type "cspc"<ENTER>
@
3.3
3.3 SPC MAIN MENU and STATUS BOX
When you execute SPC, the SPC MAIN MENU and STATUS BOX will appear
on the screen. This is the primary screen from which you will
utilize SPC. The SPC MAIN MENU contains 11 selections listed
below:
CURRENT STATUS
-------------------------------------------------
Raw Data File rand.gph
Chart Type XBAR_R
Valid Chart? Yes
Pattern Search Complete (Long)
Patterns 4
SPC MAIN MENU
A. Select Raw Data File
B. Select Chart/Diagram Type
C. View Chart/Diagram
D. Search Control Chart Menu
E. View Chart Patterns Menu
F. Expert Consultation Menu
G. More Information
H. Print Menu
I. Options
J. SPC Editor & File Manager
quit
The SPC STATUS BOX provides a summary of the results of previous
SPC MAIN MENU selections.
@
3.3.1
3.3.1 SPC MAIN MENU Option A : Select Raw Data File
Option A allows you to enter the name of the ASCII file which
contains your raw process data. See Section 3.4 for raw process
data file formats. You must create a raw data file BEFORE viewing
a graph or diagram. Several sample raw data files are included on
the SPC System Disk. The names of these files are listed below.
<filename> <chart-type>
#trun.gph#t RUN
#txmr.gph#t XMR
#tinbox.gph#t XBAR-R
#txs.gph#t XBAR-S
#tpntest.gph#t PN
#tptest.gph#t P
#tctest.gph#t C
#tutest.gph#t U
#tdivision.bar#t BAR/PARETO/PIE
#tweight.sct#t SCATTER
#tpositive.sct#t SCATTER
#tnegative.sct#t SCATTER
#thist.dat#t HISTOGRAM/CDF/POLYGON
@
3.3.2
3.3.2 SPC MAIN MENU Option B : Select Chart/Diagram Type
Option B allows you to directly select the type of control chart or
diagram that is appropriate. An automatic selection option is also
available which will make this determination for control charts
based upon the nature of your process data. When Option B is
selected, the CHART TYPE MENU will be displayed. The selections in
the CHART TYPE MENU are listed below. Either the SPC CONTROL CHART
TYPE MENU or the SPC DIAGRAM/GRAPH TYPE MENU will appear depending
upon your selection from the SPC CHART TYPE MENU.
CHART TYPE MENU
A. Control charts
B. Diagrams and Graphs
C. Return to SPC MAIN MENU
CONTROL CHART TYPE MENU
A. Automatic chart selection
B. Run chart
C. Moving Range control chart
D. Xbar-R control chart
E. Xbar-S control chart
F. pn control chart
G. p control chart
H. c control chart
I. u control chart
J. Return to SPC Main Menu
GRAPH/DIAGRAM TYPE MENU
A. Bar Graph
B. Pareto Diagram
C. Scatter Diagram
D. Histogram
E. Frequency Polygon
F. CDF or Ogive
G. Pie Chart
H. Return to SPC MAIN MENU
@
3.3.3
3.3.3 SPC MAIN MENU Option C : View Chart/Diagram
Option C allows you to view a graphic display of your control chart
or diagram.
@
3.3.4
3.3.4 SPC MAIN MENU Option D : Search Chart Patterns Menu
Option D is used to search your control chart for unusual patterns.
When you select option D, the menu to the right appears :
Documentation detailing each of these options is available by
either pressing <F1> when the menu appears or by using SPC MAIN
MENU option G (More Information) followed by option 5 (Search Chart
Patterns Menu) from the MORE INFORMATION MENU.
1. Short Search
2. Long Search
3. Retrieve Patterns From File
4. Save Current Patterns To File
5. View List of Current Patterns
6. Return To SPC Main Menu
Option D is not available for Bar Graphs, Pareto Charts, Pie
Charts, Histograms, Frequency Polygons, Ogives (CDFs), or
Scatter Diagrams.
@
3.3.5
3.3.5 SPC MAIN MENU Option E : View Patterns Menu
Option E allows you to view any unusual patterns found during the
pattern search in Option D. The patterns appear highlighted on the
graphic display of your control chart. You have the option to view
the patterns individually or all together.
Option E is not available for Bar Graphs, Pareto Charts, Pie
Charts, Histograms, Frequency Polygons, Ogives (CDFs), or
Scatter Diagrams.
@
3.3.6
3.3.6 SPC MAIN MENU Option F : Expert Consultation Menu
Option F allows you to view expert advice concerning the meaning of
any unusual patterns found in your chart (Option D). You have the
option to view advice for individual patterns or for all of the
patterns.
Option F is not available for Bar Graphs, Pareto Charts, Pie
Charts, Histograms, Frequency Polygons, Ogives (CDFs), or
Scatter Diagrams.
@
3.3.7
3.3.7 SPC MAIN MENU Option G : More Information
Option G provides on-line documentation about SPC. When Option G
is selected, the following menu will come up :
Each selection in the SPC MORE INFORMATION MENU displays several
pages of text relating to that particular subject or software
feature.
@
3.3.8
3.3.8 SPC MAIN MENU Option H : Print Menu
Option H allows you to make a paper print-out of the current chart
or diagram. More detailed help is available by pressing <F1> at
any of the printer option menus.
SPC Version 1.1 supports the following printers :
A. Epson FX/IBM Pro Printer
B. Epson LQ
C. IBM Proprinter X24
D. IBM Quietwriter
E. Toshiba P321
F. HP Laserjet/Desk Jet
G. Post Script Monochrome
H. Post Script Grayscale
I. Post Script Color
SPC Version 1.1 supports the following print orientations :
A. Half-Page
B. Land-Scape
C. Full-Page
SPC Version 1.1 supports the following print densities :
A. 75 dpi (Draft)
B. 150 dpi (Medium)
C. 300 dpi (High)
SPC Version 1.1 supports the following printer ports :
A. LPT1 (Parallel Port #1)
B. LPT2 (Parallel Port #2)
C. COM1 (Serial Port #1)
D. COM2 (Serial Port #2)
@
3.3.9
3.3.9 SPC MAIN MENU Option I : Options Menu
OPTION I HAS NOT BEEN FULLY DEVELOPED YET. Many of the items in
the OPTIONS MENU have been disabled (i.e. you cannot select them).
However, some of the options are available. These options allow
you to set various parameters which affect the performance/output
of SPC such as:
(a) Set Titles Font and Font Size
(b) Set Control Limit Type (Run charts Only)
(c) Set/Display Upper/Lower Spec. Limits (Run Only)
(d) Turn Regression Line ON/OFF (Run & Scatter Only)
(e) Turn Sound ON/OFF
(f) Display FIle Info In Graphics ON/OFF
Remember, this option is still experimental for SPC Version 1.1.
@
3.3.10
3.3.10 SPC MAIN MENU Option J : SPC Editor/File Manager
Option J allows you to edit any ASCII text file that is in the SPC
directory on your computer. You may directly edit the current raw
data file by selecting Option 1 from the SPC EDITOR MENU. If you
would like to create or edit any other ASCII text file, select
option 2 from the SPC EDIT MENU. You will then be prompted for the
name of the file you wish to edit. The SPC File Manager also
allows you to view, copy, rename, or delete any files. Detailed
help on using the SPC Editor is available from within the editor by
pressing <F1>.
@
3.3.11
3.3.11 SPC MAIN MENU Final Option : quit
Use the last Option to exit the SPC application.
@
3.4
3.4. Raw Data File Formats.
SPC will generate 8 different types of control charts -
RUN,XMR,XBAR-R,XBAR-S,PN,P,C,U and 7 diagrams - BAR, PARETO, PIE,
HISTOGRAM, Frequency POLYGON, Ogive (CDF), and SCATTER. Each type
of control chart or diagram requires a slightly different format
for the ASCII file which contains the raw process data. For all
types of charts and diagrams, entries in the raw data file must be
separated by spaces or returns. DO NOT SEPARATE ENTRIES WITH
COMMAS, ETC! The appropriate formats are outlined below.
THE FIRST FOUR LINES OF EVERY RAW DATA FILE CONTAINS THE SAME
TYPE OF INFORMATION :
Line 1 : Title
Line 2 : Subtitle
Line 3 : X (Horizontal) Axis-Label
Line 4 : Y (Vertical) Axis Label
Lines 1-4 of each raw data file may be any string of numbers
or characters you desire. The length of each line may be
anywhere from 0 characters up to 80 characters followed by a
carriage return.
@
3.4.1
3.4.1 RUN Chart Raw Data File Format
The first four lines contain title and axis label information. All
remaining entries in a RUN Chart must be numeric. The length of
the chart will be the number of entries after the first four lines.
SPC limits the number of entries in a RUN Chart to 100 or less. A
sample RUN Chart raw data file is located in the file "#trun.gph#t" on
your SPC System Disk.
@
3.4.2
3.4.2 XMR (Moving Range) Chart Raw Data File Format
The format for an XMR (Moving Range) Control Chart is identical to
the required format for the RUN Chart given in 3.4.1.
@
3.4.3
3.4.3 XBAR-R Chart Raw Data File Format
The first four lines contain title and axis label information. The
next entry (line 5) is an INTEGER between 1 and 10 inclusive. This
number represents the logical group size or sample size. The
remaining entries (REAL or INTEGER) represent the actual process
measurements. The length of the chart(s) will be the number of
process measurements divided by the logical group size. For
example, if we have a group size of 3 and 69 process measurements,
then the length of the XBAR and R Charts will be 23. Sample XBAR-R
raw data files are located in files "#tinbox.gph#t" and "#trand.gph#t" on
your SPC System Disk.
@
3.4.4
3.4.4 XBAR-S Chart Raw Data File Format
The format for an XBAR-S Control Chart is identical to the required
format for the XBAR-R Control Chart except that the logical group
(sample) size must be between 3 and 50. The raw data file format
for the XBar-R chart is given in 3.4.3.
@
3.4.5
3.4.5 PN Chart Raw Data File Format
The first four lines contain title and axis label information. All
remaining entries in a PN Chart raw data file must be INTEGERS.
The first entry represents the fixed sample size. The remaining
entries represent the number of defectives (rejects/failures) out
of the fixed number of samples. The length of the PN chart will be
one less than the number of entries in the raw data file. A sample
PN raw data file is located in the file "#tpntest.gph#t".
@
3.4.6
3.4.6 P Chart Raw Data File Format
The first four lines contain title and axis label information. All
remaining entries in a P Chart raw data file must be PAIRS of
INTEGERS. The first integer in each pair represents the sample
size and the second integer represents the number of defectives or
rejects. The length of the P Chart will be the number of pairs of
entries. A sample P raw data file is located in the file
"#tptest.gph#t".
@
3.4.7
3.4.7 C Chart Raw Data File Format
The first four lines contain title and axis label information. All
remaining entries in a C Chart raw data file must be INTEGERS.
Each entry represents the number of defects (errors) in a sample of
fixed size/weight/length/etc. The length of the C chart will be
the number of entries in the raw data file. A sample C raw data
file is located in the file "#tctest.gph#t".
@
3.4.8
3.4.8 U Chart Raw Data File Format
The first four lines contain title and axis label information. All
remaining entries in a U Chart must be PAIRS of entries. The first
entry in each pair can be either INTEGER or REAL and represents the
sample size/length/weight/etc. The second entry must be an INTEGER
and represents the number of defects/errors/etc. in the sample.
The length of the U Chart will be the number of pairs of entries.
A sample U raw data file is located in the file "#tutest.gph#t".
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3.4.9
3.4.9 Bar Graph Raw Data File Format
The first four lines contain title and axis label information. The
numeric data consists of PAIRS of entries. The first entry in each
pair can be any non-negative number, INTEGER or REAL. The second
entry in each pair can be anything - this will be the
classification name for the category that this pair represents. A
Bar Graph is limited to 20 pairs of entries. Sample Bar Graph Raw
data files are located in files "#tdivision.bar#t" and "#tsample.bar#t".
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3.4.10
3.4.10 Pareto Chart Raw Data File Format
The format for a Pareto Diagram raw data file is identical to the
required format for the Bar Graph given in 3.4.9.
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3.4.11
3.4.11 Pie Chart Raw Data File Format
The format for a PIE Chart raw data file is identical to the
required format for the Bar Graph given in 3.4.9.
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3.4.12
3.4.12 Histogram Raw Data File Format
The first four lines contain title and axis label information. The
numeric data consists of numeric entries. Each entry can be any
number, INTEGER or REAL. A Histogram is limited to 500 numeric
entries. Sample Histogram Raw data files are located in files
"#thist.dat#t" and "#tsample.dat#t".
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3.4.13
3.4.13 Frequency Polygon Raw Data File Format
The format for a Frequency Polygon raw data file is identical to
the required format for the Histogram given in 3.4.12.
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3.4.14
3.4.14 Ogive (CDF) Raw Data File Format
The format for a CDF raw data file is identical to the required
format for the Histogram given in 3.4.12.
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3.4.15
3.4.15 Scatter Diagram Raw Data File Format
The first four lines contain title and axis label information. The
numeric data consists of PAIRS of entries. Both entries in each
pair can be any number, INTEGER or REAL. The first number in each
pair will be displayed on the horizontal axis (x-axis) and the
second on the vertical axis (y-axis). A scatter diagram is limited
to 200 pairs of entries. Sample Scatter Diagram raw data files are
located in files "#tpositive.sct#t", "#tnegative.sct#t", and "#trandom.sct#t".
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4
4. POINTS OF CONTACT
If you have questions or comments concerning the SPC software,
please feel free to contact Mark Shewhart at DSN : 785-7003 or COM
: (513) 255-7003.
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5
5. REFERENCES
[1] Spyros Makridakis and Stephen C. Wheelwright, "Forecasting:
Methods and Applications",Wiley/Hamilton, 1978.
[2] Sir Maurice Kendall and J Keith Ord, "Time Series", Oxford
University Press, 1990.
[3] SPC Course Materials, Decision Dynamics Inc., 1990
[4] Kaoru Ishikawa, "Guide to Quality Control", Asian Productivity
Organization, 1982.
[5] Perry Johnson Inc., "SPC Chart Interpretation", Perry Johnson,
Inc., 1987.
[6] J.M. Juran, Dr. Frank M. Gryna, Jr., and R.S. Bingham, Jr.,
"Quality Control Handbook",Third Edition, McGraw-Hill, 1974.
[7] Western Electric Company, "Statistical Quality Control
Handbook", Western Ellectric Co., Inc., 1958.
[8] H. Besterfield, "Quality Control", Second Edition, Prentice-
Hall.
[9] Douglas C. Montogomery, "Introduction to Statistical Quality
Control".
[10] Mark Shewhart, "Application of Machine Learning and Expert
Systems to Statistical Process Control Chart Interpretation", 2nd
Annual CLIPS Conference Proceedings (1991).
[11] "The Memory Jogger : A Pocket Guide of Tools For Continuous
Improvement", GOAL/QPC, 1988.
[12] Kiemele & Schmidt, "Basic Statistics : Tools for Continuous
Improvement", Air Academy Press, Second Edition 1991.
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