Overview
The MCHART statement creates a chart for subgroup medians,
which is used to monitor the central tendency
of a process.
You can use options in the MCHART statement to
- compute control limits from the data based on a multiple of
the standard error of the plotted medians or
as probability limits
- tabulate subgroup sample sizes,
subgroup medians, control limits, and other information
- save control limits in an output data set
- save subgroup sample sizes and subgroup medians
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 one of several methods for estimating the process
standard deviation
- specify whether subgroup standard deviations or
subgroup ranges are used to estimate the process standard deviation
- specify a known (standard) process mean and standard deviation
for computing control limits
- create a secondary chart that displays a time trend
removed from the data
(see "Displaying Trends in Process Data" )
- 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
Note: When analyzing variables data, you should examine
the variability of the process as well as the mean
level. You can use the MRCHART statement
in the SHEWHART procedure to monitor both the mean level and
variability.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
