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# Re: st: Poisson Regression

 From brendan.halpin@ul.ie (Brendan Halpin) To statalist@hsphsun2.harvard.edu Subject Re: st: Poisson Regression Date Mon, 21 Feb 2011 23:55:09 +0000

```On Sun, Feb 13 2011, Alexandra Boing wrote:

> I would like to know how to proceed and the justication Mathematical and
> Statistical. My dependent variable is spent on health (0=No   1=Yes).
> The prevalence was higher than 10 percent. Can I do Poisson regression?
> According to this paper published in BMC on line in 2003, registred
> PMC521200 I can do Poisson regression with variable (0=No  1=Yes) and
> with prevalence higher than 10 percent, but other authors report that
> only I can do Poisson regression with the dependent variable= discrete
> variable and prevalence under 10 percent.
> Which is correct? And what is the explanation Mathematical and Statistical?Thanks, Alexandra

To come back belatedly to your initial question, I think this paper:

Reichenheim and Coutinho (2010) "Measures and Models for Causal
Inference in Cross-Sectional Studies: Arguments for the
Appropriateness of the Prevalence Odds Ratio and Related Logistic
Regression", BMC Medical Research Methodology

throws a lot of cold water on the idea that one should use poisson or
log-binomial instead of logistic when the baseline probability is above
0.10. They point out that while there are circumstances where log-bin,
poisson or Cox regression are correct, there is a wide range of
circumstances where logistic regression is better (and the baseline
probability is not one of the relevant criteria).

Regards,

Brendan
--
Brendan Halpin,  Department of Sociology,  University of Limerick,  Ireland
Tel: w +353-61-213147 f +353-61-202569 h +353-61-338562; Room F1-009 x 3147
mailto:brendan.halpin@ul.ie  http://www.ul.ie/sociology/brendan.halpin.html

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