BOXCHART Statement: SHEWHART Procedure
- Overview
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Getting Started
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Syntax
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Details
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Examples
Using Box Charts to Compare Subgroups Creating Various Styles of Box-and-Whisker Plots Creating Notched Box-and-Whisker Plots Creating Box-and-Whisker Plots with Varying Widths Creating Box-and-Whisker Plots with Different Line Styles and Colors Computing the Control Limits for Subgroup Maximums Constructing Multi-Vari Charts
Percentile Definitions
You can use the PCTLDEF= option to specify one of five definitions for computing quantile statistics (percentiles). Let 
equal the number of nonmissing values for a variable, and let 
represent the ordered values of the process variable. For the 
th percentile, set 
, and express 
as
 |
where 
is the integer part of , and 
is the fractional part of .
The th percentile (call it 
) can be defined in five ways, as described in the next five sections.
PCTLDEF=1
This uses the weighted average at 
 |
where 
is taken to be 
.
PCTLDEF=2
This uses the observation numbered closest to
 |
where 
is the integer part of 
.
PCTLDEF=3
This uses the empirical distribution function
 |
PCTLDEF=4
This uses the weighted average aimed at 
 |
where 
, and where 
is taken to be 
.
PCTLDEF=5
This uses the empirical distribution function with averaging
 |