Type II sums of squares are sometimes called partially sequential sums of squares. Like Type I sums of squares, Type II sums of squares for an effect controls for the influence of other effects. Which other effects to control for, however, is determined by a different criterion. In Type II sums of squares, the sums of squares for an effect is computed by controlling for the influence of all other effects of equal or lower degree. Thus, sums of squares for main effects control for all other main effects, sums of squares for two-way interactions control for all main effects and all other two-way interactions, and so on.

Unlike Type I sums of squares, Type II sums
of squares are invariant to the order in which effects are entered into
the model. This makes Type II sums of squares useful for testing hypotheses
for multiple regression designs, for main
effect ANOVA designs, for full-factorial ANOVA designs with equal cell

There is a drawback to the use of Type II sums
of squares for factorial designs with unequal cell

Whole Model Tests

Partitioning of Sums of Squares

Limitations of whole model tests

Type VI (Effective Hypothesis) Sums of Squares

Error Terms for Tests

Lack-of-Fit Tests Using Pure Error

Designs with Zero Degrees of Freedom for Error

Tests of Hypotheses in Mixed-Model Designs

Hypotheses about Linear Combinations of Effects

Planned Comparisons of Least Square Means

Testing Hypotheses for Repeated Measures and Dependent Variables

See also GLM - Index.