I have placed a set of SAS macros for generating a design matrix using PROC IML called DESMAT on my home page <http://www.socsci.kun.nl/maw/sociologie/J.Hendrickx/desmat/>.

DESMAT allows different types of parametrizations, such as the difference contrast, helmert contrast, polynomial contrast, to be used for categorical variables in the model. The design matrix can be further manipulated outside DESMAT, then exported to a SAS dataset to be used in a SAS procedure. The macros are designed to modify the output of PROC GENMOD (Generalized Linear Models) to provide information on the type of parametrization and effect labels.

These macros were developed during the course of my PhD research, in order to develop special models for square tables (Hendrickx 1994). An account of its predecessor, GLIMMAT, was presented at SEUGI 92 (Hendrickx 1992). Perhaps they will be of use to others as well.

Hendrickx, John. (1992). "Using SAS macros and PROC IML to create special designs for Generalized Linear Models." Pp. 634- 655 in SAS Institute, SEUGI '92. Proceedings of the SAS European Users Group International Conference, May 19-22, 1992.

Hendrickx, John. (1994). "The analysis of religious assortative marriage. An application of design matrix techniques for categorical models." Dissertation Nijmegen University. Amsterdam: Thesis Publishers.

John Hendrickx Department of Sociology Nijmegen University The Netherlands