The UCHART statement creates charts for the numbers of nonconformities (defects) per inspection unit in subgroup samples containing arbitrary numbers of units.

You can use options in the UCHART statement to

• specify the number of inspection units per subgroup

• compute control limits from the data based on a multiple of the standard error of the plotted values or as probability limits

• tabulate subgroup summary statistics and control limits

• save control limits in an output data set

• save subgroup summary statistics in an output data set

• read preestablished control limits from a data set

• apply tests for special causes (also known as runs tests and Western Electric rules)

• specify a known (standard) value for the average number of nonconformities per inspection unit

• display distinct sets of control limits for data from successive time phases

• add block legends and symbol markers to reveal stratification in process data

• superimpose stars at points to represent related multivariate factors

• clip extreme points to make the chart more readable

• display vertical and horizontal reference lines

• control axis values and labels

• control layout and appearance of the chart

You have three alternatives for producing charts with the UCHART statement:

• Traditional graphics are produced by default.

• ODS Graphics output is produced when you specify the ODS GRAPHICS statement prior to the PROC SHEWHART statement.

• Legacy line printer charts are produced when you specify the LINEPRINTER option in the PROC SHEWHART statement.

See Chapter 3, SAS/QC Graphics, for more information about producing these different kinds of graphs.