PROC GLIMMIX constructs a generalized linear mixed model according to the specifications in the CLASS
, MODEL
, and RANDOM
statements. Each effect in the MODEL
statement generates one or more columns in the matrix , and each G-side effect in the RANDOM
statement generates one or more columns in the matrix
. R-side effects in the RANDOM
statement do not generate model matrices; they serve only to index observations within subjects. This section shows how the
GLIMMIX procedure builds
and
. You can output the
and
matrices to a SAS data set with the OUTDESIGN=
option in the PROC GLIMMIX
statement.
The general rules and techniques for parameterization of a linear model are given in GLM Parameterization of Classification Variables and Effects in ChapterĀ 19: Shared Concepts and Topics. The following paragraphs discuss how these rules differ in a mixed model, in particular, how parameterization differs between
the and the
matrix.