The SHEWHART Procedure |

Overview |

The SCHART statement creates an chart for subgroup standard deviations, which is used to analyze the variability of a process.^{1}

You can use options in the SCHART statement to

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

tabulate subgroup sample sizes, subgroup standard deviations, control limits, and other information

save control limits in an output data set

save subgroup sample sizes, subgroup means, and subgroup standard deviations in an output data set

read preestablished control limits from a data set

specify a method for estimating the process standard deviation

specify a known (standard) process standard deviation for computing control limits

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 SCHART 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.

Footnotes

- You can also use charts for this purpose; see RCHART Statement In general, charts are recommended with large subgroup sample sizes ().

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