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UCHART Statement |

**UCHART***process***subgroup-variable*;

The general form of this syntax is as follows:**UCHART**(*processes*)**subgroup-variable*<(*block-variables*) >**<***=symbol-variable*| ='*character*' > < /*options*>;

You can use any number of UCHART statements in the SHEWHART procedure. The components of the UCHART statement are described as follows.*process**processes*-
identify one or more processes to be analyzed.
The specification of
*process*depends on the input data set specified in the PROC SHEWHART statement.- If numbers of nonconformities per subgroup
are read from a DATA=
data set,
*process*must be the name of the variable containing the numbers of nonconformities. For an example, see "Creating u Charts from Defect Count Data" . - If numbers of nonconformities per unit
and numbers of inspection units per subgroup
are read from a HISTORY= data set,
*process*must be the common prefix of the appropriate variables in the HISTORY= data set. For an example, see "Creating u Charts from Nonconformities per Unit" . - If numbers of nonconformities per item,
numbers of inspection units per subgroup,
and control limits are read
from a TABLE= data set,
*process*must be the value of the variable _VAR_ in the TABLE= data set. For an example, see "Saving Control Limits" .

A*process*is required. If you specify more than one process, enclose the list in parentheses. For example, the following statements request distinct*u*charts for DEFECTS and FLAWS:proc shewhart data=measures; uchart (defects flaws)*sample / subgroupn=50; run;

Note that when data are read from a DATA= data set with the UCHART statement, the SUBGROUPN= option (which specifies the number of inspection units per subgroup) is required. - If numbers of nonconformities per subgroup
are read from a DATA=
data set,
*subgroup-variable*-
is the variable that identifies subgroups in the data.
The
*subgroup-variable*is required. In the preceding UCHART statement, SAMPLE is the subgroup variable. For details, see "Subgroup Variables" . *block-variables*-
are optional variables that group the data into blocks of
consecutive subgroups. The blocks are labeled in a legend, and each
*block-variable*provides one level of labels in the legend. See "Displaying Stratification in Blocks of Observations" for an example. *symbol-variable*-
is an optional variable
whose levels (unique values) determine the symbol marker or character
used to plot the number of nonconformities per unit.
- If you produce a chart on a line printer,
an `A' is displayed for the points corresponding to the first level of
the
*symbol-variable*, a `B' is displayed for the points corresponding to the second level, and so on. - If you produce a chart on a graphics device,
distinct symbol markers are displayed for points
corresponding to the various levels of the
*symbol-variable*. You can specify the symbol markers with SYMBOL*n*statements. See "Displaying Stratification in Levels of a Classification Variable" for an example.

- If you produce a chart on a line printer,
an `A' is displayed for the points corresponding to the first level of
the
*character*-
specifies a plotting character for charts produced on line printers.
For example, the following statements create a
*u*chart using an asterisk (*) to plot the points:proc shewhart data=values; uchart defects*sample='*' / subgroupn=100; run;

*options*- enhance the appearance of the chart, request
additional analyses, save results in data sets, and so on.
The "Summary of Options" section, which follows, lists all
options by function. Chapter 46, "Dictionary of Options,"
describes each option in detail.

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