Linear Mixed Models Fixed Effects

This feature requires the Advanced Statistics option.

Fixed Effects. There is no default model, so you must explicitly specify the fixed effects. Alternatively, you can build nested or non-nested terms.

Include Intercept. The intercept is usually included in the model. If you can assume the data pass through the origin, you can exclude the intercept.

Sum of Squares. The method of calculating the sums of squares. For models with no missing cells, the Type III method is most commonly used.

Specifying Non-Nested Build Terms for Linear Mixed Models

  1. From the menus choose:

    Analyze > Mixed Models > Linear...

  2. Optionally, select subjects and repeated variables, and then click Continue.
  3. In the Linear Mixed Models dialog box, click Fixed or Random.
  4. Select Build terms.
  5. Select one or more factors or covariates or a combination of factors and covariates.
  6. Select a method for building the terms and click Add.
  7. Repeat the process until you have all of the terms that you want in the model.
  8. Select a type of sum of squares and whether or not you want the intercept.

Specifying Nested Build Terms for Linear Mixed Models

  1. From the menus choose:

    Analyze > Mixed Models > Linear...

  2. Optionally, select subjects and repeated variables, and then click Continue.
  3. In the Linear Mixed Models dialog box, click Fixed or Random.
  4. Select Build nested terms.
  5. Select a factor or covariate that is nested within another factor and click the move button.
  6. Click Within.
  7. Select the factor within which the previous factor or covariate is nested and click the move button.
  8. Click Add.
  9. Optionally, you can include interaction effects or add multiple levels of nesting to the nested term.