*
chapter_7_table_9

The following data is a generalization of the blood pressure data 
given in Table 7.5 (which itself was a generalization of the data 
given in Table 7.1). After the interaction is found to be significant,
a common recommendation is to examine simple main effects. Recall 
that a simple main effect is the main effect of one factor given a 
fixed level of another factor. In this case interest is in determining 
if there are any differences in drugs (a) given biofeedback and (b) 
given no biofeedback. 

Note that the LSMEAN computes least squares means for the effects 
listed in the LSMEAN statement. In this case SLICE is listed. SLICE 
tests simple main effects by "slicing" the interaction by the specified
variable. The SLICE= option specifies the effects by which to divide 
interaction LSMEAN effects. This can produce what are known as tests 
of simple effects.  
;

LIBNAME md 'd:\data files by type\sas data files\tables';
     Data c7t9;
       SET md.chapter_7_table_9;
PROC GLM DATA=c7t9;
CLASS drug feedback;
MODEL score = drug feedback drug*feedback;
LSMEANS drug*feedback / SLICE=drug; 
RUN;