Output Data Sets
The OUTLIMITS= data set saves control limits and control limit
parameters. The following variables can be saved:
Table 32.25: OUTLIMITS= Data Set
Variable

Description

_ALPHA_  probability () 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 
_LCLM_  lower control limit for subgroup median 
_LCLR_  lower control limit for subgroup range 
_LCLS_  lower control limit for subgroup standard deviation 
_LCLX_  lower control limit for subgroup mean 
_LIMITN_  nominal sample size associated with the control limits 
_LSL_  lower specification limit 
_MEAN_  process mean (value of central line on box chart) 
_R_  value of central line on R chart 
_S_  value of central line on s chart 
_SIGMAS_  multiple (k) of standard error of or M_{i} 
_STDDEV_  process standard deviation ( or ) 
_SUBGRP_  subgroupvariable specified in the BOXCHART statement 
_TARGET_  target value 
_TYPE_  type (estimate or standard value) of _MEAN_ and _STDDEV_ 
_UCLM_  upper control limit for subgroup median 
_UCLR_  upper control limit for subgroup range 
_UCLS_  upper control limit for subgroup standard deviation 
_UCLX_  upper control limit for subgroup mean 
_USL_  upper specification limit 
_VAR_  process specified in the BOXCHART statement 
Notes:
 The variables _LCLM_ and _UCLM_
are included if you specify
CONTROLSTAT=MEDIAN; otherwise,
the variables _LCLX_ and _UCLX_ are included.
 The variables _LCLS_, _S_, and _UCLS_ are included if you
specify the STDDEVIATIONS option; otherwise, the variables _LCLR_, _R_,
and _UCLR_ are included.
These variables
are not used to create box charts, but they
allow the OUTLIMITS= data set to
be used as a LIMITS= data set with the XRCHART, XSCHART,
MRCHART, SCHART, and RCHART statements.
 If the control limits vary with subgroup sample size, the special
missing value V is assigned to the variables
_LIMITN_, _LCLX_, _UCLX_, _LCLM_, _UCLM_,
_LCLR_, _R_, _UCLR_, _LCLS_, _S_,
and _UCLS_.
 If the limits are defined in terms of a multiple k of
the standard error of , the value of _ALPHA_ is computed as , where
is the standard normal distribution function.
If the limits are defined in terms of a multiple k of
the standard error of M_{i},
the value of _ALPHA_ is computed as , where F_{med}(·,n) is the cumulative distribution function of
the median of a random sample of n standard normally
distributed observations, and n is the value of _LIMITN_.
If _LIMITN_ has the special missing value V, this value
is assigned to _ALPHA_.
 If the limits for means are probability limits, the value of _SIGMAS_
is computed as , where is
the inverse standard normal distribution function.
If the limits for medians are probability limits, the value of _SIGMAS_
is computed as , where F_{med}^{1}(·,n)
is the inverse distribution function of the median of a random
sample of n standard normally distributed observations, and n
is the value _LIMITN_.
If _LIMITN_ has the special missing value V, this value
is assigned to _SIGMAS_.
 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 BOXCHART statement. For an example,
see "Saving Control Limits" .
The OUTHISTORY= data set saves subgroup summary statistics.
The following variables can be saved:
 the subgroupvariable
 a subgroup minimum variable named by the prefix process
suffixed with L
 a subgroup firstquartile variable named by the prefix process
suffixed with 1
 a subgroup mean variable named by the prefix process
suffixed with X
 a subgroup median variable named by the prefix process
suffixed with M
 a subgroup thirdquartile variable named by the prefix process
suffixed with 3
 a subgroup maximum variable named by the prefix process
suffixed with H
 a subgroup sample size variable named by the prefix
process suffixed with N
 a subgroup range variable named by the prefix process
suffixed with R or
a subgroup standard deviation variable named by
process suffixed with S
A subgroup standard deviation variable is included if you specify
the
STDDEVIATIONS option; otherwise, a subgroup range variable
is included.
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.
Subgroup summary variables are created for each process
specified in the BOXCHART statement. For example, consider
the following statements:
proc shewhart data=steel;
boxchart (width diameter)*lot / outhistory=summary;
run;
The data set SUMMARY contains variables
named LOT, WIDTHL, WIDTH1, WIDTHM, WIDTHX, WIDTH3,
WIDTHH, WIDTHR, WIDTHN, DIAMTERL, DIAMTER1, DIAMTERM,
DIAMTERX, DIAMTER3, DIAMTERH, DIAMTERR, and
DIAMTERN.
The variables WIDTHR and DIAMTERR
are included since the STDDEVIATIONS
option is not specified. If you specified the
STDDEVIATIONS option, the data set SUMMARY
would contain the variables WIDTHS and DIAMTERS
rather than WIDTHR and DIAMTERR.
Additionally, the following variables, if specified, are included:
 BY variables
 blockvariables
 symbolvariable
 ID variables
 _PHASE_ (if the OUTPHASE= option is specified)
For an example of an OUTHISTORY= data set, see
"Saving Summary Statistics" .
The OUTTABLE= data set saves subgroup summary statistics,
control limits, and related information. The following
variables can be saved:
Variable

Description

_ALPHA_  probability () of exceeding control limits 
_EXLIM_  control limit exceeded on box chart 
_LCLM_  lower control limit for median 
_LCLX_  lower control limit for mean 
_LIMITN_  nominal sample size associated with the control limits 
_MEAN_  process mean 
_SIGMAS_  multiple (k) of the standard error associated with
control limits 
subgroup  values of the subgroup variable 
_SUBMAX_  subgroup maximum 
_SUBMED_  subgroup median 
_SUBMIN_  subgroup minimum 
_SUBN_  subgroup sample size 
_SUBQ1_  subgroup first quartile (25^{ th} percentile) 
_SUBQ3_  subgroup third quartile (75^{ th} percentile) 
_SUBX_  subgroup mean 
_TESTS_  tests for special causes signaled on box chart 
_UCLM_  upper control limit for median 
_UCLX_  upper control limit for mean 
_VAR_  process specified in the BOXCHART statement 
The variables _LCLM_ and _UCLM_ are included
if you specify CONTROLSTAT=MEDIAN;
otherwise, the variables _LCLX_ and _UCLX_ are included.
In addition, the following variables, if specified, are included:
 BY variables
 blockvariables
 symbolvariable
 ID variables
 _PHASE_ (if the READPHASES= option is specified)
 _TREND_ (if the TRENDVAR= 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_, 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" .
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.