UCHART Statement: SHEWHART Procedure
Overview: UCHART Statement
The UCHART statement creates u 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
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specify the number of inspection units per subgroup
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compute control limits from the data based on a multiple of the standard error of the plotted values or as probability limits
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tabulate subgroup summary statistics and control limits
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save control limits in an output data set
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save subgroup summary statistics in an output data set
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read preestablished control limits from a data set
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apply tests for special causes (also known as runs tests and Western Electric rules)
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specify a known (standard) value for the average number of nonconformities per inspection unit
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display distinct sets of control limits for data from successive time phases
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add block legends and symbol markers to reveal stratification in process data
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superimpose stars at points to represent related multivariate factors
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clip extreme points to make the chart more readable
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display vertical and horizontal reference lines
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control axis values and labels
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control layout and appearance of the chart
You have three alternatives for producing u charts with the UCHART statement:
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ODS Graphics output is produced if ODS Graphics is enabled, for example by specifying the ODS GRAPHICS ON statement prior to the PROC statement.
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Otherwise, traditional graphics are produced by default if SAS/GRAPH® is licensed.
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Legacy line printer charts are produced when you specify the LINEPRINTER option in the PROC statement.
See Chapter 3: SAS/QC Graphics, for more information about producing these different kinds of graphs.