The Estimates tab provides a mechanism for creating custom hypothesis tests. Estimates can only be computed using the fixed effect model terms set in the Model Specification field. Since the Estimates tab produces estimates instead of contrasts, the coefficients do not have to sum to zero and more than one model term can be added to the Effect field. The marginal interval is generated for each estimate.
For more on estimates in the linear mixed effects model, see the “Estimates” section.
The Fixed Effects Model Terms box lists all the fixed effect model terms specified in the Fixed Effects tab. Drag a term from the Fixed Effect Model Terms box to the Effect field to compute the estimates for that term. The conditions for using model terms as effect variables are:
Interaction terms and nested terms can be used if they are used in the model.
If the fixed effects model includes an intercept, which is the default setting, then the intercept can be used to produce an estimate.
If the intercept term is used as an effect for an estimate it works like a regressor, which means only one coefficient value is used for the intercept.
Drag a model term from the Fixed Effect Model Terms box to the Effect field.
Multiple model terms can be dragged from the Fixed Effect Model Terms box to the Effect field.
To remove a model term, use the pointer to drag a model term from the Effect field back to the Fixed Effects Model Terms box.
In the Title field, type a title for the estimate.
The title is displayed in the Estimates and Estimates Coefficients worksheets.
In the Coefficients column, type the coefficient value for each level of the model term in the estimate.
Check the Intercept Coefficient box to include the intercept in the estimate.
In the Intercept Coefficient field, type the coefficient value for the intercept.
In the Confidence Level field, type the level percentage. The default level is 95%.
Typically, this value does not need to be changed.
To set the degrees of freedom, check the User specified degrees of freedom box and type a value greater than one (1) in the field.
Note: Only select the User specified degrees of freedom option if the Phoenix engine does not seem to use the appropriate choices for the degrees of freedom.
Check the Show coefficients of estimates box to display the actual coefficients used in the Estimates Coefficients results worksheet.
In the Estimability Tolerance field, type a value for the zero vector.
The estimability tolerance value indicates the closeness of the zero vector before the Phoenix engine is used to make it estimable. The default value is 1E–05. Typically, this value does not need to be changed.
Press Add Estimate to add another contrast.
Each estimate is tested independently of other estimates. Enter up to 100 estimates.
Press Delete Estimate to delete a contrast.