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 XCHART Statement

## Saving Cusum Scheme Parameters

 See CUSONES1 in the SAS/QC Sample Library

This example is a continuation of the previous example that illustrates how to save cusum scheme parameters in a data set specified with the OUTLIMITS= option. This enables you to apply the parameters to future data or to subsequently modify the parameters with a DATA step program.

   proc cusum data=cans lineprinter;
xchart weight*hour /
mu0    = 8.100           /* target mean              */
sigma0 = 0.050           /* known standard deviation */
delta  = 1               /* shift to be detected     */
h      = 3               /* decision interval        */
k      = 0.5             /* reference value          */
scheme = onesided        /* one-sided scheme         */
outlimits = cusparm;
label weight = 'Cusum of Weight';

proc print data=cusparm;
run;


The chart, shown in Figure 12.9, is similar to the one in Figure 12.5 but is created for output on a line printer since the LINEPRINTER option is included in the PROC CUSUM statement. *

 One-Sided Cusum Analysis

  ----------------------------------------------------------------------- 4 + | C | | u | | s | | u 3 +==============================*========================================| m | + + | | + ++ | o | + + | f 2 + + * | | + + | W | + ++ | e | + + | i 1 + * * | g | + ++ ++* | h | ++ ++ +*++ ++ | t | + *++ ++ ++ | 0 +*++++*++++*++++*++++* ++*+ *++++*| +----+----+----+----+----+----+----+----+----+----+----+----+----+----+ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Hour Subgroup Sizes: * n=1 Parameters: Mu0=8.1 Delta=1 h=3 
Figure 12.9: One-Sided Cusum Scheme with Decision Interval

The OUTLIMITS= data set is listed in Figure 12.10.

 Obs _VAR_ _SUBGRP_ _TYPE_ _LIMITN_ _H_ _K_ _SCHEME_ _MU0_ _DELTA_ _MEAN_ _STDDEV_ _ARLIN_ _ARLOUT_ 1 weight hour STANDARD 1 3 0.5 ONESIDED 8.1 1 8.09747 0.05 117.596 6.40391
Figure 12.10: Listing of the OUTLIMITS= Data Set CUSPARM

The data set contains one observation with the parameters for process WEIGHT. The variables _TYPE_, _H_, _K_, _MU0_, _DELTA_, and _STDDEV_ save the parameters specified with the options SCHEME=, H=, K=, MU0=, DELTA=, and SIGMA0=, respectively. The variable _MEAN_ saves an estimate of the process mean, and the variable _LIMITN_ saves the nominal sample size. The variables _ARLIN_ and _ARLOUT_ save the average run lengths for and for .

The variables _VAR_ and _SUBGRP_ save the process and subgroup-variable. The variable _TYPE_ is a bookkeeping variable that indicates whether the value of _STDDEV_ is an estimate or a standard value.