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Re: st: Logarithmic transformation in psm results
From
Maarten buis <[email protected]>
To
[email protected]
Subject
Re: st: Logarithmic transformation in psm results
Date
Thu, 17 Mar 2011 11:15:14 +0000 (GMT)
--- On Thu, 17/3/11, Sergio wrote:
> I'm estimating propensity score matching (with psmatch2
> routine) for a sample of firms participating in a program.
> My outcome variable (turnover of the firm) is expressed
> in logarithm <snip> How can I transform the results in
> order to interpret this results in terms of the original
> values.
You can exponeniate the ATT, but it will represent the
ratio of geometric means rather than a difference in
arithmatic means. Both geometric and arithmatic means are
valid measures of central tendency, and both a difference
and a ratio are valid ways of comparing groups, so you
could do it that way. However, it is unconventional, so you
need to spent some time/space explaining the results.
This trick, in the linear regression context, is explained
in:
Roger Newson (2003) "Stata tip 1: The eform() option of
regress". The Stata Journal, 3(4): 445.
<http://www.stata-journal.com/article.html?article=st0054>
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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