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Re: st: psmatch2: ATT as percentage change using logs?
From
Ubydul Haque <[email protected]>
To
[email protected]
Subject
Re: st: psmatch2: ATT as percentage change using logs?
Date
Thu, 15 Aug 2013 09:58:00 -0400
Hello,
I used poison regression model to explore the association of indoor
residual spraying (IRS) and long lasting insecticide treated net
(LLIN) and malaria cases. The outcome is the following:
xi: xtpoisson totalcases pc_llin prop_irs i.year, irr exp(
population) i( district_code) i.year
------------------------------------------------------------------------------
malaria cases | IRR Std. Err. z P>|z| [95% Conf. Interval]
-------------+----------------------------------------------------------------
per capita_llin | 1.185207 .0483431 4.17 0.000
1.094145 1.283848
proportion_irs | .7504642 .0696331 -3.09 0.002
.6256765 .9001402
_Iyear_2009 | .7955212 .0128567 -14.15 0.000
.7707175 .8211232
_Iyear_2010 | .6376188 .0165131 -17.38 0.000
.6060614 .6708194
_Iyear_2011 | .0790123 .0023992 -83.59 0.000
.0744472 .0838574
_Iyear_2012 | .013673 .0008019 -73.19 0.000
.0121883 .0153386
population | (exposure)
-------------+----------------------------------------------------------------
/lnalpha | 1.204061 .2083535 .7956957 1.612426
-------------+----------------------------------------------------------------
alpha | 3.333627 .6945728 2.215982 5.014964
------------------------------------------------------------------------------
Likelihood-ratio test of alpha=0: chibar2(01) = 2.6e+04 Prob>=chibar2 = 0.000
http://www.ats.ucla.edu/stat/stata/output/stata_poisson_output.htm
The probable explanation is "An additional increase IRS in coverage by
one percent will reduce malaria by a factor of XX (recalculate the
0.75 by using percentages rather than proportion), while holding LLINs
in the model constant. On the other hand every additional ITN per
capita will increase malaria by a factor of 1.19, while holding IRS in
the model constant".
Readers are interested to know the real impact of IRS and ITN to
reduce malaria cases. But can I say like this "IRS coverage was
associated with ....%/proportion/factor of reduced malaria prevalence
while ITN was associated with %/proportion/factor of increased malaria
prevalence".
Thank you.
Ubydul Haque
Post Doctoral Fellow
Johns Hopkins University
615, North Wolfe Street
Baltimore, Maryland
21218, USA
On Thu, Aug 15, 2013 at 9:25 AM, Lukas Borkowski <[email protected]> wrote:
> Dear statalist,
>
> I am using the user-written command -psmatch2- (written by Leuven and Sianesi, 2003) to estimate the ATT of my participation variable on several outcome indicators. I am also using a DiD-regression approach to estimate the ATT where I transformed some of the indicators into logs to see the percentage change caused by the treatment. I wonder whether it is also reasonable to transform the outcome indicators into logs when running -psmatch2-. Can someone give me a quick hint? Thanks!
>
> Best, Lukas
>
> Leuven, E., and Sianesi, B. (2003) PSMATCH2: Stata module to perform full Mahalanobis and propensity score matching, common support graphing, and covariate imbalance testing. Available at: http://ideas.repec.org/c/boc/bocode/s432001.html
>
> #
> Lukas Borkowski
> University of London, School of Oriental and African Studies (SOAS)
>
> M: [email protected]
>
>
>
>
> *
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--
Ubydul Haque
Post Doctoral Fellow
Johns Hopkins University
615, North Wolfe Street
Baltimore, Maryland
21218, USA
*
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