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MCHART Statement |
Other variables that can
be read from a DATA= data set include
By default, the SHEWHART procedure reads all of the observations in a DATA= data set. However, if the DATA= data set includes the variable _PHASE_, you can read selected groups of observations (referred to as phases) by specifying the READPHASES= option (for an example, see "Displaying Stratification in Phases" ).
For an example of a DATA= data set, see "Creating Charts for Medians from Raw Data" .
proc shewhart data=info limits=conlims; mchart weight*batch; run;
The LIMITS= data set can be an OUTLIMITS= data set that was created in a previous run of the SHEWHART procedure. Such data sets always contain the variables required for a LIMITS= data set. The LIMITS= data set can also be created directly using a DATA step. When you create a LIMITS= data set, you must provide one of the following:
In addition, note the following:
For an example, see "Reading Preestablished Control Limits" .
A HISTORY= data set used with the MCHART statement
must contain the following:
The names of the subgroup summary statistics variables must be the process name concatenated with the following special suffix characters:
Subgroup Summary Statistic | Suffix Character |
subgroup median | M |
subgroup mean | X |
subgroup sample size | N |
subgroup range | R |
subgroup standard deviation | S |
You must provide the subgroup mean variable only if you specify the MEDCENTRAL=AVGMEAN option. If you specify the STDDEVIATIONS option, the subgroup standard deviation variable must be included; otherwise, the subgroup range variable must be included.
For example, consider the following statements:
proc shewhart history=summary; mchart (weight yldstren)*batch / medcentral=avgmean; run;
The data set SUMMARY must include the variables BATCH, WEIGHTX, WEIGHTM, WEIGHTR, WEIGHTN, YLDSRENX, YLDSRENM, YLDSRENR, and YLDSRENN. If the STDDEVIATIONS option were specified in the preceding MCHART statement, it would be necessary for SUMMARY to include the variables BATCH, WEIGHTX, WEIGHTM, WEIGHTS, WEIGHTN, YLDSRENX, YLDSRENM, YLDSRENS, and YLDSRENN.
Note that if you specify a process name that contains eight characters, the names of the summary variables must be formed from the first four characters and the last three characters of the process name, suffixed with the appropriate character.
Other variables that can be read from a HISTORY= data set include
By default, the SHEWHART procedure reads all the observations in a HISTORY= data set. However, if the data set includes the variable _PHASE_, you can read selected groups of observations (referred to as phases) by specifying the READPHASES= option (see "Displaying Stratification in Phases" for an example).
For an example of a HISTORY= data set, see "Creating Charts for Medians from Subgroup Summary Data" .
The following table lists the variables required in a TABLE= data set used with the MCHART statement:
Table 35.25: Variables Required in a TABLE= Data SetVariable | Description |
_LCLM_ | lower control limit for median |
_LIMITN_ | nominal sample size associated with the control limits |
_MEAN_ | process mean |
subgroup-variable | values of the subgroup-variable |
_SUBMED_ | subgroup median |
_SUBN_ | subgroup sample size |
_UCLM_ | upper control limit for median |
Other variables that can be read from a TABLE= data set include
For an example of a TABLE= data set, see "Saving Control Limits" .
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