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Re: st: Recovering cell values from odds ratios


From   Maarten Buis <maartenlbuis@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Recovering cell values from odds ratios
Date   Tue, 31 May 2011 13:24:59 +0200

On Tue, May 31, 2011 at 1:06 PM, King, Carina <c.king09@imperial.ac.uk> wrote:
> I am trying to convert odds ratios back to the raw numbers. I have information on the number of cases and number of controls, as well as the odds ratios and confidence intervals.

For that you also need the baseline odds, i.e. the odds of "success"
(the expected number of successes per failure) for the controls. The
odds for the cases are the odds ratio times the baseline odds. You can
transform those odds to probabilities using the formula p = o/(1+o),
where p is probability and o = odds. From there you can compute your
counts by multiplying the probabilities with the number of controls or
cases.

Hope this helps,
Maarten

--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany


http://www.maartenbuis.nl
--------------------------
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