Defining Variables for . . .  - Quick Tab (n per sample = 1)

The Quick tab of the Defining Variables for . . . dialog box (when n per sample = 1) contains options to select the variables for the analysis, i.e., for which to compute and create quality control charts (for individual observations). To specify a multiple-parts short run chart, select either the Nominal or Standardized Short run chart type, and then specify either a Part identifier variable (with part codes/ID's) or a Constant number of samples per part.

Variables

Click the Variables button to display a standard variable selection dialog box. Depending on the selection of the Short run chart option, either a single variable list or two-variable lists selection dialog will be displayed, where you can specify 1) a list of variables for the charts and 2) an optional variable with part codes (part IDs; this choice is only provided if the Short run chart is not set to Standard, and the Constant number of samples per part check box is not selected).

Short run chart

Use the options in this box to specify a short run chart for multiple parts. These types of charts are discussed in the Introductory Overviews of the Quality Control Charts module (see Quality Control Introductory Overview - Short Run Charts).

Standard

Select the Standard option button to create a standard non-short run chart.

Nominal

Select the Nominal option button to create a nominal chart where the respective part means are subtracted from the variable values, before the charts are created.

Standardized

Select the Standardized option button to create standardized short run charts, where the sample points are standardized within each part (see also, the Glossary term Standardization).

Constant number of samples per part

If this check box is selected and no Part identifier variable is selected, you can specify here a fixed number of consecutive samples for each part. For example, if your input data consist of batches with different specifications (i.e., different parts) from which a fixed number of samples is automatically drawn, then you can select this option so that on reading the data each "chunk" of k consecutive samples is automatically assigned to the same part.

Shift to detect

This option is only available for cumulative sum (CuSum) charts for individual observations. In this field, specify the shift parameter for the chart in terms of multiples of sigma. The cumulative sum (CuSum) chart is constructed following the recommendations found in, for example, Montgomery (1996, Chapter 7; STATISTICA computes the recommended tabular or algorithmic CuSum chart, and not the "old-style" V-mask control limits). The shift value determines the shift in the mean, in terms of multiples of sigma, that you want to detect. The shift value affects the values of the plot points for the CuSum chart, as described in Quality Control Computational Details. For further recommendations regarding the CuSum chart and how to establish control limits, see Montgomery (1996; note that STATISTICA uses the recommended default of 5*Sigma or H=5 for establishing control limits).