The SHEWHART Procedure |

Overview |

The MRCHART statement creates charts for subgroup medians and ranges, which are used to analyze the central tendency and variability of a process.

You can use options in the MRCHART statement to

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

tabulate subgroup sample sizes, subgroup medians, subgroup ranges, control limits, and other information

save control limits in an output data set

save subgroup sample sizes, subgroup medians, and subgroup ranges 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 the method for estimating the process standard deviation

specify a known (standard) process mean and 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 charts 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 of medians and ranges with the MRCHART 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.

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