Interaction Terms

Click the Interaction terms button in the Weight of Evidence (WoE) dialog box to display the Interaction Terms dialog box, which contains options to specify recoding of interactions to a single continuous variable with WoE values. By default, when a new two-way  interaction table is created, Statistica automatically uses the CHAID algorithm to combine those groups that have similar WoE values.

The settings for the CHAID algorithm can be modified in the Settings dialog box.

Multiple two-way interactions can be specified via this dialog box.

  1. Add new interaction term.
  2. Click this button to define a new interaction term. A variable selection dialog box displays,
  3. Specify the two variables for the new interaction. Note that the interaction table is constructed from the respective coded (continuous, categorical) predictor variables, as selected in the Weight of Evidence (WoE) dialog box (see the Choose group type option description).

Example: If the variable Age is chosen for the two-way interaction table, and the Linear constraint coding is selected for Age, the interaction table is constructed from the linear constraint coded predictor variable.

Identification of Merged Groups

The individual groups in the two-way table will be color coded and labeled to identify which groups were merged. Specifically, by default all groups in the two-way table will be labeled row-by-row as G1, G2, ..., Gn. When combined, groups are labeled as Gi+Gj+...+Gk, and will share common color coding.

Note: You can also move the cursor over any field in this dialog box, to see the WoE values and other summary statistics for (combined) groups.

Select Cells, Clear Grouping, Merge Cells

To use the interaction tables, click on individual cells to select them, and then click the

  • Group button to merge the respective cells  from their current group (of other cells)
  • Ungroup button  to remove the respective cells from their current group (of other cells).

Statistica will automatically compute the new WoE values for the un/grouped cells based on the respective data in the groups.

Hide/Show

  • Click the Hide button to hide the interaction table on the left. The button will change to the Show button.
  • Click the Show button to show the interaction table on the left. The button will change to the Hide button.

Delete

Click this button to delete the respective interaction table on the left.

Optimal Grouping

Click this button to apply Optimal Grouping via the CHAID algorithm (see the WoE Introductory Overview) to the selected groups.

Clear Grouping

Click this button to clear all grouping, (to remove all merged cells and restore the original two-way table).

Group, Ungroup

Click these buttons to Group selected cells or to Ungroup selected cells from others in the respective group.

Clear Selection

Click this button to clear the current selection of cells in the two-way table.

Comments

Add or edit comments in this box. Only text can be used, and cannot exceed 2,000 characters. The comments will  display in the header of the custom crosstabulation output and in the header of the interaction grid output.

OK

Click this button to save the respective current interaction coding for all interaction tables specified in this dialog box.

Cancel

Click this button to abandon any changes to the specification for coding interactions.