SPSS® 12.0 Command Syntax Reference

132 ANOVA
Example
The following analysis list specifies three factor variables named A, B, and C:
ANOVA VARIABLES=Y BY A,B,C(0,3).
Table 1 summarizes the three methods for decomposing sums of squares for this example.
• With the default regression approach, each factor or interaction is assessed with all other
factors and interactions held constant.
• With the classic experimental approach, each main effect is assessed with the two other
main effects held constant, and two-way interactions are assessed with all main effects
and other two-way interactions held constant. The three-way interaction is assessed with
all main effects and two-way interactions held constant.
• With the hierarchical approach, the factor main effects A, B, and C are assessed with all
prior main effects held constant. The order in which the factors and covariates are listed on
the ANOVA command determines the order in which they are assessed in the hierarchical
analysis. The interaction effects are assessed the same way as in the experimental approach.
Table 1 Terms adjusted for under each option
Effect Regression
(UNIQUE)
Experimental Hierarchical
A All others B,C None
B All others A,C A
C All others A,B A,B
AB All others A,B,C,AC,BC A,B,C,AC,BC
AC All others A,B,C,AB,BC A,B,C,AB,BC
BC All others A,B,C,AB,AC A,B,C,AB,AC
ABC All others A,B,C,AB,AC,BC A,B,C,AB,AC,BC
Summary of Analysis Methods
Table 2 describes the results obtained with various combinations of methods for controlling
entry of covariates and decomposing the sums of squares.