Output Data Sets :: SAS/QC(R) 12.1 User's Guide

OUTLIMITS= Data Set

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

Table 17.15: OUTLIMITS= Data Set

Variable	Description
`_ALPHA_`	probability ( $\alpha$ ) of exceeding limits
`_C_`	value of central line on c chart ( $n_{i}\bar{u}$ or $n_{i}u_{0}$ )
`_INDEX_`	optional identifier for the control limits specified with the OUTINDEX= option
`_LCLC_`	lower control limit for number of nonconformities
`_LIMITN_`	sample size associated with the control limits
`_SIGMAS_`	multiple (k) of standard error of $c_{i}$
`_SUBGRP_`	subgroup-variable specified in the CCHART statement
`_TYPE_`	type (estimate or standard value) of `_U_`
`_U_`	average number of nonconformities per unit ( $\bar{u}$ or $u_{0}$ )
`_UCLC_`	upper control limit for number of nonconformities
`_VAR_`	process specified in the CCHART statement

Notes:

If the control limits vary with subgroup sample size, the special missing value V is assigned to the variables _C_, _LCLC_, _UCLC_, and _LIMITN_.
If the limits are defined in terms of a multiple k of the standard error of $c_{i}$ , the value of _ALPHA_ is computed as $P\{ c_ i<\_ \mbox{LCLC}\_ \} + P\{ c_ i>\_ \mbox{UCLC}\_ \}$ . If control limits vary with subgroup sample size and are determined in terms of k, _ALPHA_ is assigned the special missing value V.
If the limits are probability limits, the value of _SIGMAS_ is computed as $(\_ \mbox{UCLC}\_ - \_ \mbox{C}\_ )/\sqrt {\_ \mbox{C}\_ }$ . If probability limits vary with subgroup sample size, _SIGMAS_ is assigned the special missing value V.
Optional BY variables are saved in the OUTLIMITS= data set.

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

OUTHISTORY= Data Set

The OUTHISTORY= data set saves subgroup statistics. The following variables are saved:

the subgroup-variable
a subgroup sample size variable named by process suffixed with N
a subgroup number of nonconformities per unit variable named by process suffixed with U

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 CCHART statement. For example, consider the following statements:

proc shewhart data=Fabric;
   cchart (Flaws Ndefects)*lot / outhistory=Summary;
run;

The data set SUMMARY contains variables named LOT, FlawsU, FlawsN, NDEFCTSU, and NDEFCTSN. 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 that creates an OUTHISTORY= data set, see Saving Nonconformities per Unit. Note that an OUTHISTORY= data set created with the CCHART statement can be used as a HISTORY= data set by either the CCHART statement or the UCHART statement.

OUTTABLE= Data Set

The OUTTABLE= data set saves subgroup summary statistics, control limits, and related information. The following variables are saved:

Variable	Description
`_ALPHA_`	probability ( $\alpha$ ) of exceeding control limits
`_C_`	average number of nonconformities
`_EXLIM_`	control limit exceeded on c chart
`_LCLC_`	lower control limit for number of nonconformities
`_LIMITN_`	nominal sample size associated with the control limits
`_SIGMAS_`	multiple (k) of the standard error associated with control limits
subgroup	values of the subgroup variable
`_SUBC_`	subgroup number of nonconformities
`_SUBN_`	subgroup sample size
`_TESTS_`	tests for special causes signaled on c chart
`_UCLC_`	upper control limit for number of nonconformities
`_VAR_`	process specified in the CCHART 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 kth character of a value of _TESTS_ is k if Test k is positive at that subgroup. For example, if you request the first four tests (the ones appropriate for c charts) and Tests 2 and 4 are positive for a given subgroup, the value of _TESTS_ has a 2 for the second character, a 4 for the fourth 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.

CCHART Statement: SHEWHART Procedure

Output Data Sets

OUTLIMITS= Data Set

OUTHISTORY= Data Set

OUTTABLE= Data Set