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st: RE: How to "reverse" log transformated result
From
"Jesper Lindhardsen" <[email protected]>
To
<[email protected]>
Subject
st: RE: How to "reverse" log transformated result
Date
Wed, 28 Sep 2011 13:14:57 +0200
Hi Morten,
I may have misunderstood, but as you do not provide your syntax and/or exact regression method, it is hard to know.
My guess is that the first result is a ratio from comparing groups, while the other result could be an estimate at the mean values in the two groups.
As Nick suggested the rate of being granted a disability pension, may be easier to model.
Just my thoughts,
Jesper
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Morten Støver
Sent: 28 September 2011 09:41
To: [email protected]
Subject: st: How to "reverse" log transformated result
I'm doing an multilevel linear regression analysis where I try to
investigate if there are variation in the lenght of the rehabilitation
process before people are being granted a disability pension. I measure
this in days, and since my data are very skewed, I've done a log
transformation. Now I wonder how I can transform the results back to the
original scale of measurement. As an example, this are the results for
the different types of diagnosis.
"Other" diagnosis: (ref)
Mental disorders: 0.1993938
Musulosceletal: 0.0840664
If I now try to transform the data back using di exp(.1993938) I get the
result 1.2206626.
If I try to analyse the data without log transforming them, I find that
the mental disorders group have 166 days (95% CI: 75.5-265.6) longer
rehabilitation time before being granted a disability pension than the
"other" diagnosis group.
I guess that the di exp is not the right way to transform the results
back, but I don't know any other way to do it.
I'm using Stata 11.
Thank you for your help
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