Re: How to calculate OR from estimated coefficients of a multinomial log regression?

gothamjack08@xxxxxxxxx wrote:
Hi all

I am a total novice with regard to more complex statistics.

I was wondering if there is a way to calculate adjusted OR and their
95%CI from the estimated coefficients of a multinomial logistic
regression (by use of STATA). There's a publication where this has
been
done (Lancet. 2004 Sep 11-17;364(9438):937-52). However, this study
was a case-control study.

Preferring OR over RRR for interpretation, I would like to do the same
for a retrospective cohort study for which I have run a multinomial
log regression model (since I have a multilevel dependant variable).
But I am not sure if this is possible and correct to do at all,
respectively.

Thanks for any help!

I'm not very well versed in Stata, but I suspect you're using the mlogit procedure, right? Here is its help file:

http://www.stata.com/help.cgi?mlogit

And here are some examples of its use:

http://www.ats.ucla.edu/stat/stata/examples/alr/alrstata8.htm

According to the help file, "mlogit, rr" generates a report of "relative-risk ratios". But the "relative-risk ratios" in those examples are equal to Exp(b) from the preceding output. That seems a bit odd to me, because Exp(b) in a logistic regression is usually described as giving the odds ratio.

This has me wondering if you're running into a terminological issue here. I know that some epidemiology books when discussing case-control studies give the formula for the odds ratio ((ad)/(bc)), but call the result a relative risk (presumably because in a case-control study, the OR provides a good estimate of the RR). Could it be that the Stata documentation is doing the same thing?

HTH.

--
Bruce Weaver
bweaver@xxxxxxxxxxxx
www.angelfire.com/wv/bwhomedir
"When all else fails, RTFM."
.

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