Random Effects (generalized linear mixed models)
Random effects factors are fields whose values in the data file can be considered a random sample from a larger population of values. They are useful for explaining excess variability in the target. By default, if you have selected more than one subject in the Data Structure tab, a Random Effect block will be created for each subject beyond the innermost subject. For example, if you selected School, Class, and Student as subjects on the Data Structure tab, the following random effect blocks are automatically created:
- Random Effect 1: subject is school (with no effects, intercept only)
- Random Effect 2: subject is school * class (no effects, intercept only)
You can work with random effects blocks in the following ways:
- To add a new block, click Add Block... This opens the Random Effect Block (generalized linear mixed models) dialog.
- To edit an existing block, select the block you want to edit and click Edit Block... This opens the Random Effect Block (generalized linear mixed models) dialog.
- To delete one or more blocks, select the blocks you want to delete and click the delete button.