# BOXCHART Statement: ANOM Procedure

#### Saving Decision Limits

See ANMBXLIM in the SAS/QC Sample LibraryYou can save the decision limits for an ANOM chart, together with the parameters used to compute the limits, in a SAS data set.

The following statements read measurements from the data set LabelDeviations (see Creating ANOM Boxcharts from Response Values.) and save the decision limits displayed in Figure 4.3 in a data set named LabelLimits:

proc anom data=LabelDeviations;
boxchart Deviation*Position / outlimits=LabelLimits
nochart;
run;


The OUTLIMITS= option names the data set containing the decision limits, and the NOCHART option suppresses the display of the chart. The data set LabelLimits is listed in Figure 4.7.

Figure 4.7: The Data Set LabelLimits Containing Decision Limit Information

 Decision Limits for Labler Position Deviations

_VAR_ _GROUP_ _TYPE_ _LIMITN_ _ALPHA_ _LDLX_ _MEAN_ _UDLX_ _MSE_ _DFE_ _LIMITK_
Deviation Position ESTIMATE 10 0.05 -.009875811 .009996667 0.029869 .000643787 54 6

The data set LabelLimits contains one observation with the limits for response Deviation. The values of _LDLX_ and _UDLX_ are the lower and upper decision limits for the means, and the value of _MEAN_ is the weighted average of the group means, which is represented by the central line.

The values of _MEAN_, _MSE_, _DFE_, _LIMITK_, _LIMITN_, and _ALPHA_ are the parameters used to compute the decision limits. The value of _MSE_ is the mean square error, and the value of _DFE_ is the associated degrees of freedom. The value of _LIMITK_ is the group size (k), the value of _LIMITN_ is the nominal sample size associated with the decision limits, and the value of _ALPHA_ is the value of the significance level (). The variables _VAR_ and _GROUP_ are bookkeeping variables that save the response and group-variable. The variable _TYPE_ is a bookkeeping variable that indicates whether the values of _MEAN_ and _MSE_ are estimates computed from the data or standard (known) values specified with procedure options. In most applications, the value of _TYPE_ will be 'ESTIMATE.'

See ANMBXTAB in the SAS/QC Sample LibraryYou can create an output data set containing both decision limits and group summary statistics with the OUTTABLE= option, as illustrated by the following statements:

proc anom data=LabelDeviations;
boxchart Deviation*Position / outtable=LabelTab
nochart;
run;


The data set LabelTab is listed in Figure 4.8.

Figure 4.8: The Data Set LabelTab

 Summary Statistics and Decision Limits

_VAR_ Position _ALPHA_ _LIMITN_ _SUBN_ _LDLX_ _SUBX_ _MEAN_ _UDLX_ _EXLIM_ _SUBMIN_ _SUBQ1_ _SUBMED_ _SUBQ3_ _SUBMAX_
Deviation 1 0.05 10 10 -.009875811 -0.02234 .009996667 0.029869 LOWER -0.0647 -0.0362 -0.02620 -0.0016 0.0094
Deviation 2 0.05 10 10 -.009875811 0.01625 .009996667 0.029869   -0.0332 -0.0201 0.02045 0.0438 0.0564
Deviation 3 0.05 10 10 -.009875811 0.00604 .009996667 0.029869   -0.0440 -0.0139 0.00570 0.0285 0.0486
Deviation 4 0.05 10 10 -.009875811 0.06473 .009996667 0.029869 UPPER 0.0362 0.0530 0.06030 0.0755 0.1073
Deviation 5 0.05 10 10 -.009875811 0.00813 .009996667 0.029869   -0.0464 -0.0074 0.00760 0.0302 0.0374
Deviation 6 0.05 10 10 -.009875811 -0.01283 .009996667 0.029869 LOWER -0.0384 -0.0285 -0.00950 0.0017 0.0071

This data set contains one observation for each group sample. The variable _SUBMIN_ contains the group minimums, and the variable _SUBQ1_ contains the first quartile for each group. The variables _SUBX_ and _SUBMED_ contain the group means and medians. The variable _SUBQ3_ contains the third quartiles, _SUBMAX_ contains the group maximums, and _SUBN_ contains the group sample sizes. The variables _LDLX_ and _UDLX_ contain the lower and upper decision limits, and the variable _MEAN_ contains the central line. The variables _VAR_ and Position contain the response name and values of the group-variable, respectively. For more information, see OUTTABLE= Data Set.

An OUTTABLE= data set can be read later as a TABLE= data set. For example, the following statements read LabelTab and display an ANOM boxchart (not shown here) identical to the chart in Figure 4.3:

title 'Analysis of Label Deviations';
proc anom table=LabelTab;
xchart Deviation*Position;
label _SUBX_ = 'Mean Deviation from Center (mm)';
run;


Because the ANOM procedure simply displays the information in a TABLE= data set, you can use TABLE= data sets to create specialized ANOM boxcharts.