You can use the **Variables** tab to specify the variables for the Logistic Regression analysis. The **Variables** tab is shown in Figure 23.2.

The analysis handles two types of models. For *single-trial syntax*,
you specify a single binary variable as the response variable. This variable can be character or numeric. For *events/trials syntax*, you specify two numeric variables that contain count data for a binomial experiment.
The value of the first variable is the number of positive responses (or *events*).
The value of the second variable is the number of *trials*.

The dialog box supports multiple explanatory variables. You can include nominal variables in the model by adding them to the You can include interval variables in the model by adding them to the list.

list.When you add an explanatory variable, that main effect is added to the **Effects** tab. You can add interaction effects and nested effects by using the **Effects** tab.