The basic syntax for the UCHART statement is as follows:
- 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.
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;
Note that when data are read from a DATA= data set with the
the SUBGROUPN= option (which specifies the number of inspection
units per subgroup) is required.
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" .
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.
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 SYMBOLn statements.
See "Displaying Stratification in Levels of a Classification Variable" for an example.
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;
- 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.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.