Derived variables
Derived variables are variables that are created from other variables using an expression. For example, you might create a numeric derived variable to show the sum of the values stored in two or more other numeric variables.
There are two varieties of derived variables:
▪Dynamically derived variables: These are defined in the metadata only and do not actually exist in the case data. After they have been defined in the metadata, they can be queried through the Case Data Model just like any other variable, but the return values are calculated “on the fly”.
However, generally the term derived variable is used to mean a dynamically derived variable.
This section provides examples of creating both dynamically derived variables and persisted derived variables. The examples use the Museum sample data set, which is installed with the UNICOM Intelligence Developer Documentation Library. By default it is in:
[INSTALL_FOLDER]\IBM\SPSS\DataCollection\7\DDL\Data\Data Collection File\
See also