You use the Define Derived Element dialog box to enter the calculation for a derived element, which derives its value from that of other categories in the variable. To open the Define Derived Element dialog box, select the derived element on the Edit tab in the Edit Variable dialog box (see Edit Variable dialog box), the New Variable dialog box (see New Variable dialog box), or Edit Axis dialog box (see Edit Axis dialog box, and then click Edit Item in the Specification column.

For example, to create a category "55 and over" derived from the sum of the two categories 55-64 years and 65+ years, enter the calculation (using the category names, not the labels):

Derived elements use an arithmetic expression based on the values of other categories in the table. This differs from using an expression in a user-defined category, which uses a logical expression that tests the case data to determine whether a respondent is included in the count.