Categorical Regression Discretization
The Discretization dialog box allows you to select a method of recoding your variables. Fractional-value variables are grouped into seven categories (or into the number of distinct values of the variable if this number is less than seven) with an approximately normal distribution unless otherwise specified. String variables are always converted into positive integers by assigning category indicators according to ascending alphanumeric order. Discretization for string variables applies to these integers. Other variables are left alone by default. The discretized variables are then used in the analysis.
Method. Choose between grouping, ranking, and multiplying.
- Grouping. Recode into a specified number of categories or recode by interval.
- Ranking. The variable is discretized by ranking the cases.
- Multiplying. The current values of the variable are standardized, multiplied by 10, rounded, and have a constant added so that the lowest discretized value is 1.
Grouping. The following options are available when discretizing variables by grouping:
- Number of categories. Specify a number of categories and whether the values of the variable should follow an approximately normal or uniform distribution across those categories.
- Equal intervals. Variables are recoded into categories defined by these equally sized intervals. You must specify the length of the intervals.
To Specify CATREG Discretization
This feature requires the Categories option.
- From the
menus choose:
- In the Categorical Regression dialog box, click Discretization.
- Select the variable(s) that you want to discretize and choose the method(s).
- Click Change.
- Repeat until all variables have the method you want.
- Click Continue.