Output Data Sets

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IRCHART Statement

Output Data Sets

OUTLIMITS= Data Set

The OUTLIMITS= data set saves control limits and control limit parameters. The following variables can be saved:

Table 34.23: OUTLIMITS= Data Set

Variable	Description
_ALPHA_	probability ( $\alpha$ ) of exceeding limits
_CP_	capability index C_p
_CPK_	capability index C_pk
_CPL_	capability index CPL
_CPM_	capability index C_pm
_CPU_	capability index CPU
_INDEX_	optional identifier for the control limits specified with the OUTINDEX= option
_LCLI_	lower control limit for individual measurements
_LCLR_	lower control limit for moving ranges
_LIMITN_	number of consecutive measurements used to compute moving ranges
_LSL_	lower specification limit
_MEAN_	process mean
_R_	value of central line on moving range chart
_SIGMAS_	multiple (k) of standard error of individual measurement or moving range
_STDDEV_	process standard deviation ( $\hat{\sigma}$ or $\sigma_{0}$ )
_SUBGRP_	subgroup-variable specified in the IRCHART statement
_TARGET_	target value
_TYPE_	type (estimate or standard value) of _MEAN_ and _STDDEV_
_UCLI_	upper control limit for individual measurements
_UCLR_	upper control limit for moving ranges range
_USL_	upper specification limit
_VAR_	process specified in the IRCHART statement

Notes:

If the limits are defined in terms of a multiple k of the standard errors of X_i and R_i, the value of _ALPHA_ is computed as $\alpha=2(1-\Phi(k))$ , where $\Phi(\cdot)$ is the standard normal distribution function.
If the limits are probability limits, the value of _SIGMAS_ is computed as $k=\Phi^{-1}(1-\alpha/2)$ , where $\Phi^{-1}$ is the inverse standard normal distribution function.
The variables _CP_, _CPK_, _CPL_, _CPU_, _LSL_, and _USL_ are included only if you provide specification limits with the LSL= and USL= options. The variables _CPM_ and _TARGET_ are included if, in addition, you provide a target value with the TARGET= option. See "Capability Indices" for computational details.
Optional BY variables are saved in the OUTLIMITS= data set.

The OUTLIMITS= data set contains one observation for each process specified in the IRCHART statement. For an example, see "Saving Control Limits" .

OUTHISTORY= Data Set

The OUTHISTORY= data set saves individual measurements and moving ranges. The following variables are saved:

the subgroup-variable
an individual measurements variable named by process
a moving range variable named by process suffixed with R

Given a process name that contains eight characters, the procedure first shortens the name to its first four characters and its last three characters, and then it adds the suffix. For example, the procedure shortens the process DIAMETER to DIAMTER before adding the suffix R.

A variable containing the moving ranges is created for each process specified in the IRCHART statement. For example, consider the following statements:

   proc shewhart data=steel;
      irchart (width diameter)*lot / outhistory=summary;
   run;

The data set SUMMARY contains variables named LOT, WIDTH, WIDTHR, DIAMETER, and DIAMTERR.

Additionally, the following variables, if specified, are included:

BY variables
block-variables
symbol-variable
ID variables
_PHASE_ (if the OUTPHASE= option is specified)

For an example of an OUTHISTORY= data set, see "Saving Individual Measurements and Moving Ranges" .

OUTTABLE= Data Set

The OUTTABLE= data set saves individual measurements, moving ranges, control limits, and related information. The following variables are saved:

Variable Description

_ALPHA_ probability ( $\alpha$ ) of exceeding control limits

_EXLIM_ control limit exceeded on individual measurements chart

_EXLIMR_ control limit exceeded on moving range chart

_LCLI_ lower control limit for individual measurements

_LCLR_ lower control limit for moving range

_LIMITN_ number of consecutive measurements used to compute moving ranges

_MEAN_ process mean

_R_ average range

_SIGMAS_ multiple (k) of the standard error associated with control limits

subgroup values of the subgroup variable

_SUBI_ individual measurement

_SUBR_ moving range

_TESTS_ tests for special causes signaled on individual measurements chart

_UCLI_ upper control limit for individual measurements

_UCLR_ upper control limit for moving range

_VAR_ process specified in the IRCHART statement

In addition, the following variables, if specified, are included:

BY variables
block-variables
symbol-variable
ID variables
_PHASE_ (if the READPHASES= option is specified)

Notes:

Either the variable _ALPHA_ or the variable _SIGMAS_ is saved, depending on how the control limits are defined (with the ALPHA= or SIGMAS= options, respectively, or with the corresponding variables in a LIMITS= data set).
The variable _TESTS_ is saved if you specify the TESTS= option. The k^th character of a value of _TESTS_ is k if Test k is positive at that subgroup. For example, if you request all eight tests and Tests 2 and 8 are positive for a given subgroup, the value of _TESTS_ has a 2 for the second character, an 8 for the eighth character, and blanks for the other six characters.
The variables _VAR_, _EXLIM_, _EXLIMR_, and _TESTS_ are character variables of length 8. The variable _PHASE_ is a character variable of length 16. All other variables are numeric.

For an example, see "Saving Control Limits" .

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