You use the Define Derived Element dialog 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, select the derived element on the Edit tab in the Edit Variable dialog (see Edit Variable dialog), the New Variable dialog (see New Variable dialog), or Edit Axis dialog (see Edit Axis dialog, 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.