I have an unbalanced dataset (4 groups in total, of which 3 groups consist of 8 rats and one group consists of 7 rats). I want to run a mixed ANOVA (type III) with the Car package. My dataset has 3 factors: Day (10 levels, within-subject factor), Sex (2 levels, between-subject factor) and Group (2 levels, between-subject factor). My dependent variable is Weight.