o What is step-down MANOVA?
Step-down MANOVA, also called the Roy-Bargman Stepdown F test, is a conservative approach to significance testing of the main effects, designed to prevent the inflation of Type I errors (thinking you have something when you do not). Stepdown tests perform a univariate analysis of the significance of the first dependent, then test the second dependent controlling for the first as a covariate, and so on, sequentially rotating the dependents to the status of covariates. This process continues until one encounters a significant F for a variable, leading the researcher to conclude it is significantly related to the independent (classification) variables over and above the "covaried out" previously-tested dependent variables. Step-down MANOVA is recommended only when there is an à priori theoretical basis for ordering the dependent (criterion) variables. The order of the variables is critical to the results obtained by this method. In SPSS syntax mode, specify PRINT SIG(STEP) to obtain the stepdown F test. As of SPSS Version 10, it was not available in menu mode but using GLM one could obtain identical results by conducting multiple runs, each time with a different dependent as covariate.
In SPSS, make sure that the dependents are entered in the desired order, then in the MANOVA syntax, enter PRINT SIGNIF(STEPDOWN) or simply PRINT SIG(STEP). For example: