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BOXCHART Statement |
By default, the SHEWHART procedure reads all of the observations in a DATA= data set. However, if the data set includes the variable _PHASE_, you can read selected groups of observations (referred to as phases) with the READPHASES= option (for an example, see "Displaying Stratification in Phases" ).
For an example of a DATA= data set, see "Creating Box Charts from Raw Data" .
proc shewhart data=info limits=conlims; boxchart 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; see Table 32.25. 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 BOXCHART statement
must contain the following:
If you specify the STDDEVIATIONS option, the subgroup standard deviation variable must be included; otherwise, the subgroup range variable must be included.
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 minimum | L |
subgroup first-quartile | 1 |
subgroup median | M |
subgroup mean | X |
subgroup third-quartile | 3 |
subgroup maximum | H |
subgroup sample size | N |
subgroup range | R |
subgroup standard deviation | S |
proc shewhart history=summary; boxchart (weight yldstren)*batch; run;
The data set SUMMARY must include the variables BATCH, WEIGHTL, WEIGHT1, WEIGHTM, WEIGHTX, WEIGHT3, WEIGHTH, WEIGHTR, WEIGHTN, YLDSRENL, YLDSREN1, YLDSRENM, YLDSRENX, YLDSREN3, YLDSRENH, YLDSRENR, and YLDSRENN.
If the STDDEVIATIONS option were specified in the preceding BOXCHART statement, it would be necessary for SUMMARY to include the variables WEIGHTS and YLDSRENS rather than WEIGHTR and YLDSRENR.
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 of 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) with the READPHASES= option (see "Displaying Stratification in Phases" for an example).
For an example of a HISTORY= data set, see "Creating Box Charts from Subgroup Summary Data" .
The following table lists the variables required in a TABLE= data set used with the BOXCHART statement:
Table 32.27: Variables Required in a TABLE= Data SetVariable | Description |
_LCLM_ | lower control limit for median |
_LCLX_ | lower control limit for mean |
_LIMITN_ | nominal sample size associated with the control limits |
_MEAN_ | process mean |
subgroup-variable | values of the subgroup-variable |
_SUBMAX_ | subgroup maximum |
_SUBMIN_ | subgroup minimum |
_SUBMED_ | subgroup median |
_SUBN_ | subgroup sample size |
_SUBQ1_ | subgroup first quartile (25^{ th} percentile) |
_SUBQ3_ | subgroup third quartile (75^{ th} percentile) |
_SUBX_ | subgroup mean |
_UCLM_ | upper control limit for median |
_UCLX_ | upper control limit for mean |
Note that if you specify CONTROLSTAT=MEDIAN, the variables _LCLM_, _SUBMED_, and _UCLM_ are required; otherwise, the variables _LCLX_, _SUBX_, and _UCLX_ are required.
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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