Defining Variables for Hotelling T-Square (Means)/GV Chart - Sets Tab

Select the Sets tab of the Defining Variables for Hotelling T-Square (Means)/GV Chart dialog box to access the following options.

Variable with IDs or Labels to Identify Sets. Note that the options on the Specs tab are used to specify a mean vector and variance/covariance matrix (sigma) for the overall multivariate chart. When sets are specified, the sigma matrix is computed from the respective samples or observations identified as belonging to the respective same set. As a result, when sets are specified, specifications on the Specs tab of this dialog are ignored.

Option Description
Set labels Click Set labels to display a standard variable selection dialog box where you can select the variable that is used in determining sets. This variable can contain predefined labels, for example, set1, set2. It can also contain a sequence of values that Statistica can use to periodically create new sets. Note that a new set is also created if specification or control limits change, even if the Set label has not changed.
Create new set when set label equals to In certain applications, sets are identified by a cycling sequence number rather than a label. For example, samples are taken every ten minutes and within any given hour, the sample is labeled as 1, 2, 3, 4, 5, or 6. To create sets based on the samples taken in one hour, select Create new set when set label equals to check box and enter 1 in the adjacent box. Each time the sample number goes back to 1, a new set is started. If this value is set, any other changes in the set identifier are ignored. A new set starts only when the set identifier transitions back to the specific value, for example 1. Note that a new set is also created if specification or control limits change.
Calculate Sigma from first k samples in the set; k = By default, the process sigma (matrix) is calculated on a per set basis using every sample in the set. If you want to calculate sigma using only the first k samples in each set, select the Calculate Sigma from first k samples in the set check box and enter a value for k in the adjacent k= box. Note that the value for k is uniform across all sets.
Chart specs vars for sets Displays the Defining Sets, Specifications for Charts from Variables dialog box. Use the options in this dialog to define the variable specifications (multivariate Center line, or mean vector), control limits, and warning limits (defined as p values for this type of chart). Note that set specifications are optional. When these values are defined, sets are automatically be created when specs change in consecutive samples.
Clear set label/specs Clears the selections made via the Set labels option and the Chart specs vars for sets option.