ABSTRACT
All models considered in previous chapters have contained only random effects. In this chapter we consider several mixed models that contain both fixed and random effects. Sections 7. 2-7.6 consider balanced mixed models and Section 7. 7 provides some results for unbalanced models. As in balanced random models, confidence intervals on variance components in balanced mixed models are based on independent mean squares from the ANOVA table. These mean squares have scaled chi-squared distributions and expected values that contain the variance components but not the fixed effects. Hence, confidence intervals on variance components in mixed models are formed in exactly the same manner as in random models.
