CCHART Statement

Overview

The CCHART statement creates c charts for the numbers of nonconformities (defects) in subgroup samples.

You can use options in the CCHART statement to

specify the number of inspection units per subgroup. Typically (but not necessarily), each subgroup consists of a single unit.
compute control limits from the data based on a multiple of the standard error of the counts 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 the layout and appearance of the chart