Which analysis to choose?

[maria_sas]

Hi

I´m new to SAS and statistical analyses. I hope I´m posting in the right  forum.

I´m trying to perform a logistic regression on my data.

My dataset contains patients with a chronic disease and a controlgroup. They are pooled in no disease=1, light disease=2 and severe disease=3 (90 patients and 250 controls, matched by age groups). I want to investige the relation to impotence, impotent=1, not impotent=2 

My statement is as follows:

proc logistic data = controlsandpatients;
class disease (ref = "1") / param=ref ;
model impotent (event = "1") = disease / lackfit ;
run;

I get a quasi-complete separation problem, The maximum likelihood estimate may not exist. I´ve tried to do an exact test, but that doesen´t solve the problem. Is this the right way to analyse this or should i use PROC FREQ?

I hope you can help me

Best regards 

Maria

[Ksharp]

Since you have control group, do you consider to use conditional logistic regression ?

[maria_sas]

Thanks for your reply.

I am new to sas programming, and have never done a conditional logistic regression - I tried looking in sas support pages but I am not sure how I would set it up? 

[Ksharp]

There is an example in Documentation about conditional LR.

I remember you should use STRATA statement .

[maria_sas]

Thanks!