How to compare the differences of relapse_count in proc genmod?

[Lucai_sister]

Hello, guys. I just learned SAS, and I have been puzzled for many days. I hope you can help me.

My data is the number of relapses(Y) in different treatment groups (group=1,2,3) , and I want to compare the difference in the number of relapses in different treatment groups under the least squares mean estimation. I used the lsmeans statement to compare the differences. It outputs the difference of the estimated coefficient(Beta1-Beta3, Beta2-Beta3). But I want to get the differences of Y.

my data is like:

id   group   relapse_count   lntime 

1         1             0                          -1.108

2        2             1                           -0.693

3        3             1                           -3.218

4        2             2                          -1.108

.........

here is my SAS codes:

proc genmod data=a;
class group(ref="3") id/param=glm;
model relapse_count=group/link=log dist=negbin offset=lntime;
repeated subject=id;
lsmeans group/cl ilink exp ;
estimate '2-1' group -1 1 0/exp;
estimate '1-3' group 1 0 -1/exp;
estimate '2-3' group 0 1 -1/exp;

run;

I would appreciate it if you could help me!

[Ksharp]

http://support.sas.com/kb/24/188.html

[Ksharp]

If you want RiskDiff ,check this url:
https://support.sas.com/kb/37/228.html

[Lucai_sister]

Thank you for your reply, which makes it more clear that what I want to ask for is the rate rather than the count difference. But I don't know why the NLMeans macro is used. In my opinion it is just more convenient to call. Does it help to find the difference in rates? Thank you very much for your guidance.

[Ksharp]

Then check my second URL.