# Generalized Linear Models Options

These options are applied to all factors specified on the Predictors tab.

**User-Missing Values.** Factors
must have valid values for a case to be included in the analysis. These controls
allow you to decide whether user-missing values are treated as valid among
factor variables.

**Category Order.**
This is relevant for determining a factor's last level, which may be associated
with a redundant parameter in the estimation algorithm. Changing the category
order can change the values of factor-level effects, since these parameter
estimates are calculated relative to the “last” level. Factors
can be sorted in ascending order from lowest to highest value, in descending
order from highest to lowest value, or in "data order." This means that the
first value encountered in the data defines the first category,
and the last unique value encountered defines the last category.

How To Specify Options for Factors in Generalized Linear Models

- From the menus choose:
...or Generalized Estimation Equations

- Click the Predictors tab.
- In the Predictors tab, click Options.