SPSS® 12.0 Command Syntax Reference

1612 UNIANOVA
• B1 versus B2 at A1. In the first LMATRIX subcommand, the difference is tested between
levels 1 and 2 of effect B when effect A is fixed at level 1. Since there are three levels each
in effects A and B, the interaction effect A*B takes up nine columns in the design matrix.
• Effect A. In the second LMATRIX subcommand, effect A is tested. Since there are three levels
in effect A, at most two independent contrasts can be formed; thus, there are two rows in
the L matrix, which are separated by a semicolon (;). The first row tests the difference
between levels 1 and 3 of effect A, while the second row tests the difference between levels
2 and 3 of effect A.
• B1 versus B2 at A2. In the last LMATRIX subcommand, the keyword ALL is used. The first
0 corresponds to the intercept effect; the next three zeros correspond to effect A.
KMATRIX Subcommand
The KMATRIX subcommand allows you to customize your hypothesis tests by specifying the
K matrix (contrast results matrix) in the general form of the linear hypothesis LB = K. The
vector B is the parameter vector in the linear model.
• The default K matrix is a zero matrix; that is, LB = 0 is assumed.
• For the KMATRIX subcommand to be valid, at least one of the following subcommands
must be specified: the LMATRIX subcommand or the INTERCEPT = INCLUDE
subcommand.
• If KMATRIX is specified but LMATRIX is not specified, the LMATRIX is assumed to take the
row vector corresponding to the intercept in the estimable function, provided the subcommand
INTERCEPT = INCLUDE is specified. In this case, the K matrix can be only a scalar
matrix.
• If KMATRIX and LMATRIX are specified, then the number of rows in the requested K and
L matrices must be equal. If there are multiple LMATRIX subcommands, then all requested
L matrices must have the same number of rows, and K must have the same number of
rows as these L matrices.
• A semicolon (;) can be used to indicate the end of a row in the K matrix.
• If more than one KMATRIX subcommand is specified, only the last one is in effect.
Example
UNIANOVA DEP BY A B
/LMATRIX = “Effect A”
A 1 0 -1; A 1 -1 0
/LMATRIX = “Effect B”
B 1 0 -1; B 1 -1 0
/KMATRIX = 0; 0
/DESIGN = A B.
In this example, assume that factors A and B each have three levels.
• There are two LMATRIX subcommands; both have two rows.
• The first LMATRIX subcommand tests whether the effect of A is 0, while the second
LMATRIX subcommand tests whether the effect of B is 0.
• The KMATRIX subcommand specifies that the K matrix also has two rows, each with value 0.