topic Re: How to use proc logistic to estimate probability difference -- or common risk difference in SAS Procedures

How to use proc logistic to estimate probability difference -- or common risk difference

HappySASUE — Fri, 21 Feb 2020 02:04:25 GMT

I try to use proc logistic regression to estimate the probability difference between placebo and treatment group. It gives me odds ratio difference, how can I change to risk difference?

Also any difference between "risk difference" or "proportional difference" or "probability difference" between proc freq and proc logistic?

Thanks,

Re: How to use proc logistic to estimate probability difference -- or common risk difference

Ksharp — Fri, 21 Feb 2020 04:22:53 GMT

Better post it at Statistical Forum ,since it is about stat . @StatDave @Rick_SAS is there .

If your data is contingency table , like

placebo treatment

good 12 23

bad 2 3

you could try

PROC FREQ;

table group*good_bad / riskdiff ;

run;

"risk difference" is for 12/(23+12) V.S. 2/(2+3) or 23/(23+12) V.S. 3/(2+3)

"proportional difference"(a.k.a odds ratio) is for 12/23 V.S. 2/3

Re: How to use proc logistic to estimate probability difference -- or common risk difference

HappySASUE — Fri, 21 Feb 2020 04:31:04 GMT

Thank you!
Actually I find a very useful link. it explained everything:
http://support.sas.com/kb/37/228.html