Regression Approach (ANOVA command)

All effects are assessed simultaneously, with each effect adjusted for all other effects in the model. This is the default when the METHOD subcommand is omitted. Since MCA tables cannot be produced when the regression approach is used, specifying MCA or ALL on STATISTICS with the default method triggers a warning.

Some restrictions apply to the use of the regression approach:

• The lowest specified categories of all the independent variables must have a marginal frequency of at least 1, since the lowest specified category is used as the reference category. If this rule is violated, no ANOVA table is produced and a message identifying the first offending variable is displayed.
• Given an n-way crosstabulation of the independent variables, there must be no empty cells defined by the lowest specified category of any of the independent variables. If this restriction is violated, one or more levels of interaction effects are suppressed and a warning message is issued. However, this constraint does not apply to categories defined for an independent variable but not occurring in the data. For example, given two independent variables, each with categories of 1, 2, and 4, the (1,1), (1,2), (1,4), (2,1), and (4,1) cells must not be empty. The (1,3) and (3,1) cells will be empty but the restriction on empty cells will not be violated. The (2,2), (2,4), (4,2), and (4,4) cells may be empty, although the degrees of freedom will be reduced accordingly.

To comply with these restrictions, specify precisely the lowest non-empty category of each independent variable. Specifying a value range of (0,9) for a variable that actually has values of 1 through 9 results in an error, and no ANOVA table is produced.