GLM and MANOVA Syntax - Keyword SSType 

Optional keyword; specify how to construct the hypotheses for the tests of main effects and interactions; for the sigma-restricted model (PARAM =SIGMA) the default value is 6 (unique or effective hypothesis decomposition; see Hocking, 1985) and option 4 is not valid; for the overparameterized model (PARAM =OVERP) the default value is 3 (orthogonal; see Goodnight, 1980), and option 6 is not valid. Option BALANCED is only applicable to balanced between designs (see Huge balanced ANOVA for a definition of "eligible" designs), and will greatly speed up the computations for huge designs (see Balanced ANOVA in the Introductory Overview). For a description and discussion of the different options for constructing main effect and interaction hypotheses in unbalanced and incomplete designs, see also Six types of sums of squares.