Random Effects Formula Advanced Dialog
Variables
Group Variables
Select the grouping factor(s). Multiple grouping factors can be entered for multi-level models.
Random Terms
Select the random effects from the dropdown list.
Transformation
Click this button to open the Transformation dialog, where you can create new variables based on mathematical transformations of variables in your data set.
Add
Add Formula
After selecting variables in the fields above, click the Add Formula button to add the formula to the Group Formulas field below.
Group Formulas
As formulas are formed by selecting a Group Variable and corresponding Random Terms or Covariance Structures they are added to this field. The formulas are of the form group = ~ random-term, in general. They are passed to the Model page, as a list of formulas specifying the random effects part of the model.
Covariance Structure
Cov. Type
Different positive-definite matrix structures can be used to represent the random effects variance-covariance matrix. Select a type from the dropdown menu below:
Cov Type Select a positive-definite matrix structure for the random effects variance-covariance. Choose from General Symmetric, Diagonal, Multiple of an Identity, Compound Symmetric (constant diagonal and constant off-diagonal elements), or Block Diagonal, Option (S-PLUS function), Banded (pdBand), or Kronecker (pdKron).
Remove
Use these buttons to remove formulas from the Group Formulas field.