The OUTLIMITS= data set saves control limits and control limit parameters. The following variables can be saved:
Table 17.67: OUTLIMITS= Data Set
Variable 
Description 


probability () of exceeding limits 

capability index 

capability index 

capability index 

capability index 

capability index 

optional identifier for the control limits specified with the OUTINDEX= option 

lower control limit for subgroup range 

lower control limit for subgroup standard deviation 

lower control limit for subgroup mean 

sample size associated with the control limits 

lower specification limit 

process mean ( or ) 

value of central line on R chart 

value of central line on s chart 

multiple (k) of standard error of 

process standard deviation ( or ) 

subgroupvariable specified in the XCHART statement 

target value 

type (estimate or standard value) of 

upper control limit for subgroup range 

upper control limit for subgroup standard deviation 

upper control limit for subgroup mean 

upper specification limit 

process specified in the XCHART statement 
Notes:
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 charts, but they enable the OUTLIMITS= data set to be used as a LIMITS= data set with the BOXCHART, MRCHART, RCHART, SCHART,
XRCHART, and XSCHART statements.
If the control limits vary with subgroup sample size, the special missing value 'V' is assigned to the variables _LIMITN_
, _LCLX_
, _UCLX_
, _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 probability limits, the value of _SIGMAS_
is computed as , where 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 XCHART 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 mean variable named by process suffixed with X
a subgroup sample size variable named by process suffixed with N
a subgroup range variable named by process suffixed with R
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 32 characters, the procedure first shortens the name to its first 16 characters and its last 15 characters, and then it adds the suffix.
Subgroup summary variables are created for each process specified in the XCHART statement. For example, consider the following statements:
proc shewhart data=Steel; xchart (Width Diameter)*Lot / outhistory=Summary; run;
The data set Summary
contains variables named Lot
, WidthX
, WidthR
, WidthN
, DiameterX
, DiameterR
, and DiameterN
. The variables WidthR
and DiameterR
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 DiameterS
rather than WidthR
and DiameterR
.
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 


probability () of exceeding control limits 

control limit exceeded on chart 

lower control limit for mean 

nominal sample size associated with the control limits 

process mean 

multiple (k) of the standard error associated with control limits 
subgroup 
values of the subgroup variable 

subgroup sample size 

subgroup mean 

tests for special causes signaled on chart 

upper control limit for mean 

process specified in the XCHART statement 
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= option, respectively, or with the corresponding
variables in a LIMITS= data set).
The variable _TESTS_
is saved if you specify the TESTS= option. The kth 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 _EXLIM_
and _TESTS_
are character variables of length 8. The variable _PHASE_
is a character variable of length 48. The variable _VAR_
is a character variable whose length is no greater than 32. All other variables are numeric.
For an example, see Saving Control Limits.