CPM
Name:
Type:
Purpose:
Compute the process capability index (CPM) for a variable.
Description:
The process capability index measure the performance (i.e., the
capability) of an industrial process. The CPM is a variant of
the CP and CPK capability indices.
where USL and LSL are user specified upper and lower
specification limits, TARGET is the target engineering limit,
and s are the sample mean and standard deviation of the
data. For this statistic, larger is better.
The specification limits define the range within which a
product is considered acceptable (values outside this range
indicate that a product is defective).
Syntax:
LET <par> = CPM <y>
<SUBSET/EXCEPT/FOR qualification>
where <y> is the response variable;
<par> is a parameter where the computed CPM is
stored;
and where the <SUBSET/EXCEPT/FOR qualification> is optional.
Examples:
LET A = CPM Y1
LET A = CPM Y1 SUBSET TAG > 2
Note:
The upper and lower specification limits and target value
must be specified by the user as follows:
LET LSL = <value>
LET USL = <value>
LET TARGET = <value>
Note:
This statistic is also supported for the following plots:
CPM PLOT Y X
DEX CPM PLOT Y X1 ... Xk
You need to specify the LSL, USL, and TARGET values (see
above) before entering these commands. For more information
on these plots, enter
HELP STATISTIC PLOT
HELP DEX PLOT
Default:
Synonyms:
Related Commands:
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CONTROL CHART
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= Generate a control chart.
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STATISTIC PLOT
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= Generate a statistic versus subset plot.
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DEX PLOT
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= Generate a dex plot.
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CP (LET)
|
= Compute the process capability index.
|
|
CPK (LET)
|
= Compute the process capability index.
|
|
CPNK (LET)
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= Compute the process capability index.
|
|
CC (LET)
|
= Compute the process capability index.
|
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PERCENT DEFECTIVE (LET)
|
= Compute the percentage of defectives in a sample.
|
|
EXPECTED LOSS (LET)
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= Compute the expected loss of a sample.
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Reference:
"Guide to Quality Control", Kaoru Ishikawa, Asian Productivity
Organization, 1982 (chapter 13).
Applications:
Implementation Date:
Program:
SKIP 25
READ GEAR.DAT Y X
LET LSL = 0.995
LET USL = 1.005
LET TARGET = 1.0
CHARACTER X BLANK
LINE BLANK SOLID
TITLE AUTOMATIC
CPM PLOT Y X
Date created: 6/5/2001
Last updated: 4/4/2003
Please email comments on this WWW page to
alan.heckert@nist.gov.
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