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SCHART Statement |
Variable | Description |
_ALPHA_ | probability () of exceeding limits |
_CP_ | capability index C_{p} |
_CPK_ | capability index C_{pk} |
_CPL_ | capability index CPL |
_CPM_ | capability index C_{pm} |
_CPU_ | capability index CPU |
_INDEX_ | optional identifier for the control limits specified with the OUTINDEX= option |
_LCLS_ | lower control limit for subgroup standard deviation |
_LCLX_ | lower control limit for subgroup mean |
_LIMITN_ | sample size associated with the control limits |
_LSL_ | lower specification limit |
_MEAN_ | process mean ( or ) |
_S_ | value of central line on s chart |
_SIGMAS_ | multiple (k) of standard error of or s_{i} |
_STDDEV_ | process standard deviation ( or ) |
_SUBGRP_ | subgroup-variable specified in the SCHART statement |
_TARGET_ | target value |
_TYPE_ | type (estimate or standard value) of _MEAN_ and _STDDEV_ |
_UCLS_ | upper control limit for subgroup standard deviation |
_UCLX_ | upper control limit for subgroup mean |
_USL_ | upper specification limit |
_VAR_ | process specified in the SCHART statement |
Notes:
The OUTLIMITS= data set contains one observation for each process specified in the SCHART statement. For an example, see "Saving Control Limits" .
The subgroup mean variable is included so that the data set can be reused as a HISTORY= data set with the BOXCHART, XCHART, and XSCHART statements, as well as the SCHART statement.
Given a process name that contains eight characters, the procedure first shortens the name to its first four characters and its last three characters, and then it adds the suffix. For example, the procedure shortens the process DIAMETER to DIAMTER before adding the suffix.
Subgroup summary variables are created
for each process specified in the SCHART
statement. For example, consider the following statements:
proc shewhart data=steel; schart (width diameter)*lot / outhistory=summary; run;
The data set SUMMARY contains variables named LOT, WIDTHX, WIDTHS, WIDTHN, DIAMTERX, DIAMTERS, and DIAMTERN.
Additionally, the following variables, if specified, are included:
For an example of an OUTHISTORY= data set, see "Saving Summary Statistics" .
Variable | Description |
_ALPHA_ | probability () of exceeding control limits |
_EXLIM_ | control limit exceeded on s chart |
_LCLS_ | lower control limit for standard deviation |
_LIMITN_ | nominal sample size associated with the control limits |
_S_ | average standard deviation |
_SIGMAS_ | multiple (k) of the standard error associated with control limits |
subgroup | values of the subgroup variable |
_SUBN_ | subgroup sample size |
_SUBS_ | subgroup standard deviation |
_TESTS2_ | tests for special causes signaled on s chart |
_UCLS_ | upper control limit for standard deviation |
_VAR_ | process specified in the SCHART statement |
In addition, the following variables, if specified, are included:
Notes:
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