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Two questions about glm and counts

To: s-news@lists.biostat.wustl.edu
Subject: Two questions about glm and counts
From: Tristan Lorino <tristan.lorino@lcpc.fr>
Date: Wed, 20 Apr 2005 09:09:02 +0200
Organization: LCPC
Reply-to: Tristan Lorino <tristan.lorino@lcpc.fr>
Hi,

I  have  four  categorical  variables  (A,  B, C and D) in column, and
around  1,000 observations. Variables "B", "C" and "D" are covariates,
and  variable  "A" the variable to explain. I computed crosstables for
A-B,  A-C and A-D: each chi-square are significant. Now I  would  like
to   perform   a   model  with  all  the  covariates in the same time.
I   think  that  glm  should  be a good choice. But I cannot find the
good   family/link   option:  "poisson"  family  seems  to be only for
counts   (this   is  not  the  case  here) and "binomial" family (with
"logit"  link) is only for binary outcomes (all my variables have more
than 2 levels).

The  aim  is  to analyze the joint impact of the three covariates, and
maybe to determine the covariate the "most related" to A.

Another question  still remains to me: how can I create a new file
with five  columns, the first fourth presenting all the possible combinations
of  the  levels  of    my    four   variables (i.e. one combination by
line),   and   the  fifth   column   (say E) containing the  amount of
observations for each combination?

Thank you in advance,
Tristan Lorino

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