SPSS® 12.0 Command Syntax Reference

MANOVA: Univariate 867
with similar interactions between TREATMNT and the continuous variables and between
the AGE by TREATMNT interaction and the continuous variables.
• If the last term is not statistically significant, there is no evidence that the regression of Y on
X1 and X2 is different across any combination of the categories of AGE and TREATMNT.
Error Terms for Individual Effects
The “error” sum of squares against which terms in the design are tested is specified on the
ERROR subcommand. For any particular term on a DESIGN subcommand, you can specify a
different error term to be used in the analysis of variance. To do so, name the term followed
by the keyword VS (or AGAINST) and the error term keyword.
• To test a term against only the within-cells sum of squares, specify the term followed by
VS WITHIN on the DESIGN subcommand. For example, GROUP VS WITHIN tests the
effect of the factor GROUP against only the within-cells sum of squares. For most analyses,
this is the default error term.
• To test a term against only the residual sum of squares (the sum of squares for all terms
not included in your DESIGN), specify the term followed by VS RESIDUAL.
• To test against the combined within-cells and residual sums of squares, specify the term
followed by VS WITHIN+RESIDUAL.
• To test against any other sum of squares in the analysis of variance, include a term corresponding
to the desired sum of squares in the design and assign it to an integer between
1 and 10. You can then test against the number of the error term. It is often convenient to
test against the term before you define it. This is perfectly acceptable as long as you define
the error term on the same DESIGN subcommand.
Example
MANOVA DEP BY A, B, C (1,3)
/DESIGN=A VS 1,
B WITHIN A = 1 VS 2,
C WITHIN B WITHIN A = 2 VS WITHIN.
• In this example, the factors A, B, and C are completely nested; levels of C occur within levels
of B, which occur within levels of A. Each factor is tested against everything within it.
• A, the outermost factor, is tested against the B within A sum of squares, to see if it contributes
anything beyond the effects of B within each of its levels. The B within A sum of
squares is defined as error term number 1.
• B nested within A, in turn, is tested against error term number 2, which is defined as the
C within B within A sum of squares.
• Finally, C nested within B nested within A is tested against the within-cells sum of
squares.
User-defined error terms are specified by simply inserting = n after a term, where n is an
integer from 1 to 10. The equals sign is required. Keywords used in building a design term,
such as BY or WITHIN, are evaluated first. For example, error term number 2 in the above
example consists of the entire term C WITHIN B WITHIN A. An error-term number, but
not an error-term definition, can follow the keyword VS.