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PROC CAPABILITY and General Statements

Output Data Set


The OUTTABLE= data set saves univariate statistics and capability indices. The following variables can be saved:

Variable Description
_CP_capability index Cp
_CPK_capability index Cpk
_CPL_capability index CPL
_CPM_capability index Cpm
_CPU_capability index CPU
_K_capability index K
_LSL_lower specification limit
_NMISS_number of missing observations
_N_number of nonmissing observations
_P1_1 st percentile
_P5_5 th percentile
_P10_10 th percentile
_P90_90 th percentile
_P95_95 th percentile
_P99_99 th percentile
_PCTGTR_percentage of observations greater than upper specification limit
_PCTLSS_percentage of observations less than lower specification limit
_Q1_25 th percentile (lower quartile)
_Q3_75 th percentile (upper quartile)
_QRANGE_interquartile range (upper quartile minus lower quartile)
_SGNRNK_centered sign rank
_STD_standard deviation
_SUMWGT_sum of the weights
_TARGET_target value
_USL_upper specification limit
_VAR_variable name

Note: The variables _CP_, _CPK_, _CPL_, _CPM_, _CPU_, _K_, _LSL_, _PCTGTR_, _PCTLSS_, _TARGET_, and _USL_ are included if you provide specification limits.

The OUTTABLE= data set and the OUT= data set*

for details on the OUT= data set. contain essentially the same information. However, the structure of the OUTTABLE= data set may be more appropriate when you are computing summary statistics or capability indices for more than one process variable in the same invocation of the CAPABILITY procedure. Each observation in the OUTTABLE= data set corresponds to a different process variable, and the variables in the data set correspond to summary statistics and indices.

See CAPTAB1 in the SAS/QC Sample Library

For example, suppose you have ten process variables (P1-P10). The following statements create an OUTTABLE= data set named TABLE, which contains summary statistics and capability indices for each of these variables:

   proc capability data=process outtable=table noprint;
      var p1-p10;
      specs lsl=  5  10  65  35  35   5  25  25  60  15
            usl=175 275 300 450 550 200 275 425 500 525;

The following statements create the table shown in Figure 1.4, which contains the mean, standard deviation, lower and upper specification limits, and capability index Cpk for each process variable:

   proc print data=table label noobs;
      var _VAR_ _MEAN_ _STD_ _LSL_ _USL_ _CPK_;
      label _VAR_='Process';

Process Mean Standard Deviation Lower Specification
Upper Specification
Capability Index
p1 90.76 57.024 5 175 0.49242
p2 167.32 81.628 10 275 0.43972
p3 224.56 96.525 65 300 0.26052
p4 258.08 145.218 35 450 0.44053
p5 283.48 157.033 35 550 0.52745
p6 107.48 52.437 5 200 0.58814
p7 153.20 90.031 25 275 0.45096
p8 217.08 130.031 25 425 0.49239
p9 280.68 140.943 60 500 0.51870
p10 243.24 178.799 15 525 0.42551
Figure 1.4: Tabulating Results for Multiple Process Variables

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Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.