PROC CAPABILITY and General Statements
The DATA= data set contains a set of variables that represent measurements from a process. The CAPABILITY procedure must have a DATA= data set. If you do not specify one with the DATA= option in the PROC CAPABILITY statement, the procedure uses the last data set created.
The SPEC= option in the PROC CAPABILITY statement identifies a SPEC= data set, which contains specification limits. This option is an alternative to using the SPEC statement. If you use both the SPEC= option and a SPEC statement, the SPEC= option is ignored. The SPEC= option is especially useful when:
-
the number of variables is large
-
the same specification limits are referred to in more than one analysis
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a BY statement is used
-
batch processing is used
The following variables are read from a SPEC= data set:
|
Variable |
Description |
|---|---|
|
_LSL_ |
lower specification limit |
|
_TARGET_ |
target value |
|
_USL_ |
upper specification limit |
|
_VAR_ |
name of the variable |
You may omit either _LSL_ or _USL_ but not both. _TARGET_ is optional. If the SPEC= data set contains both _LSL_ and _USL_, you can assign missing values to _LSL_ or _USL_ to indicate one-sided specifications. You can assign missing values to _TARGET_ when the variable does not use a target value. _LSL_, _USL_, and _TARGET_ must be numeric variables. _VAR_ must be a character variable.
You can include the following optional variables in a SPEC= data set to control the appearance of specification limits on charts:
|
Variable |
Description |
|---|---|
|
_CLEFT_ |
color used to fill area left of LSL (histograms only) |
|
_CLSL_ |
color of LSL line |
|
_CRIGHT_ |
color used to fill area right of USL (histograms only) |
|
_CTARGET_ |
color of target line |
|
_CUSL_ |
color of USL line |
|
_LLSL_ |
line type of LSL line |
|
_LSLSYM_ |
character used for LSL line in line printer plots |
|
_LTARGET_ |
line type of target line |
|
_LUSL_ |
line type of USL line |
|
_PLEFT_ |
pattern type used to fill area left of LSL (histograms only) |
|
_PRIGHT_ |
pattern type used to fill area right of USL (histograms only) |
|
_TARGETSYM_ |
character used for target in line printer plots |
|
_USLSYM_ |
character used for USL line in line printer plots |
|
_WLSL_ |
width of LSL line |
|
_WTARGET_ |
width of target line |
|
_WUSL_ |
width of USL line |
If you are using the HISTOGRAM statement to create "clickable" histograms in HTML, you can also provide the following variables in a SPEC= data set:
|
Variable |
Description |
|---|---|
|
_LOURL_ |
URL associated with area to left of lower specification limit |
|
_HIURL_ |
URL associated with area to right of upper specification limit |
|
_URL_ |
URL associated with area between specification limits |
These are character variables whose values are Uniform Resource Locators (URLs) linked to areas on a histogram. When you view the ODS HTML output with a browser, you can click on an area, and the browser will bring up the page specified by the corresponding URL.
If you use a BY statement, the SPEC= data set must also contain the BY variables. The SPEC= data set must be sorted in the same order as the DATA= data set. Within a BY group, specification limits for each variable plotted are read from the first observation where _VAR_ matches the variable name.
See the section Examples: CAPABILITY Procedure for an example of reading specification limits from a SPEC= data set.
In the CAPABILITY procedure, you can add features to traditional graphics plots by specifying ANNOTATE= data sets either in the PROC CAPABILITY statement or in individual plot statements. Depending on where you specify an ANNOTATE= data set, however, the information is used for all plots or only for plots produced by a given statement.
Information contained in the ANNOTATE= data set specified in the PROC CAPABILITY statement is used for all plots produced in a given PROC step; this is a "global" ANNOTATE= data set. By using this global data set, you can keep information common to all plots in one data set.
Information contained in the ANNOTATE= data set specified in a plot statement is used for plots produced by that statement; this is a "local" ANNOTATE= data set. By using this data set, you can add statement-specific features to plots. For example, you can add different features to plots produced by the HISTOGRAM and QQPLOT statements by specifying an ANNOTATE= data set in each plot statement.
In addition, you can specify an ANNOTATE= data set in the PROC CAPABILITY statement and in plot statements. This enables you to add some features to all plots (those given in the data set specified in the PROC statement) and also add statement-specific features to plots (those given in the data set specified in the plot statement).
For complete details on the structure and content of Annotate type data sets, see SAS/GRAPH documentation.