Date: Wed, 17 Oct 2007 13:59:35 0400
ReplyTo: DJR <rizzolod@HOTMAIL.COM>
Sender: "SAS(r) Discussion" <SASL@LISTSERV.UGA.EDU>
From: DJR <rizzolod@HOTMAIL.COM>
Subject: help with an estimate statement in GENMOD
ContentType: text/plain; charset=ISO88591
Hello SASL subscribers:
I am trying to output an estimate from a generalized linear model fit in SAS
GENMOD. The model relates the binary response to a continuous variable
(time, in minutes: 1,2,...,60) and a categorical variable with 3 levels
(STAGE, listed in a class statement). The specific model of interest is:
model Y = time time*time time*STAGE time*time*STAGE / dist=B link=logit LRCI;
My goal is get an estimate of the response over a range of times with the
STAGE effects averagedout. I am using an estimate statement to attempt
this. For example, at time=1, I have written the estimate statement as follows:
estimate “time=1” intercept 1
time 1
time*time 1
time*STAGE 0.33 0.33 0.33
time*time*STAGE 0.33 0.33 0.33;
for time=2:
estimate “time=2” intercept 1
time 2
time*time 4
time*STAGE 0.66 0.66 0.66
time*time*STAGE 1.33 1.33 1.33;
and I repeat this across the range of times I am interested in. I get the
estimates that I am after, except for the value of time=1, which gives “no
est.” I have used this code with similar data before. Because, the code
works (or seems to work) for other values of time, I suspected it was a
problem with the dataset, but I checked it and found no errors. Is this
approach to averaging out the stage effect correct (i.e., the coefficient in
the estimate statement being set to the value of time*time*0.333), and if
so, what might the problem at the of value time=1 be?
Thanks for the help.
DJR
