Example (CSLOGISTIC command)

Suppose that dependent variable Y is binary, and factors A and B each have three levels.

CSLOGISTIC y BY a b
  /PLAN FILE='/survey/myfile.csplan'
  /MODEL a b a*b
  /CUSTOM  LABEL = ‘Effect A’
     LMATRIX = a 1 0 -1
       a*b  1/3  1/3  1/3
            0    0    0
           -1/3 -1/3 -1/3;
       a 0 1 -1
       a*b  0    0    0
            1/3  1/3  1/3
           -1/3 -1/3 -1/3.
  • The preceding syntax specifies a test of effect A.
  • Because there are three levels in effect A, two independent contrasts can be formed at most; thus, there are two rows in the L matrix, separated by a semicolon (;).
  • There are three levels each in effects A and B; thus, the interaction effect A*B takes nine columns in the design matrix.
  • The first row in the L matrix tests the difference between levels 1 and 3 of effect A; the second row tests the difference between levels 2 and 3 of effect A.
  • The KMATRIX keyword is not specified, so the null hypothesis value for both tests is 0.