[S] Generalized Linear Model for Clustered Observations

Gerald Haeubl (Gerald.Haeubl@ualberta.ca)
Thu, 24 Sep 1998 11:32:41 -0600 (MDT)

Hello all,

I wonder if anybody on s-news may be able to offer advice with respect to
the following problem:

My objective is to model the effects of four binary predictors on a set of
dependent variables. Each predictor represents a 2-level factor in the
design of a controlled experiment. Three of these predictors reflect
between-subjects factors, while the fourth corresponds to a within-subject
factor. Some of the dependent variables are frequencies; others are binary
responses. Thus, I would like to fit poisson and logistic regression
models, respectively, using the glm function in S-Plus (4.5 Professional for
Windows). However, since the design contains a 2-level within-subject
factor, the two sets of responses obtained from each individual should not
be treated as independent. As far as I know, glm does not allow for a
repeated measures setup that would take into account the clustered nature of
the data. If the dependent variables were continuous, I would be inclined
to use the lme function and specify subjects as the experimental units. It
seems that what I am looking for is a function that combines the virtues of
glm (allowing non-continuous response variables) and lme (allowing clustered

Any advice on this would be appreciated tremendously.

Gerald Haeubl

Gerald Haeubl
Faculty of Business
University of Alberta
Edmonton, Alberta
Canada T6G 2R6
Voice: (403) 492-6886 (office)
Voice: (403) 432-1708 (home office)
Fax: (403) 492-3325
E-mail: Gerald.Haeubl@ualberta.ca
WWW: http://www.bus.ualberta.ca/ghaeubl

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