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RE: st: RE: Poisson Regression
From
Alexandra Boing <[email protected]>
To
[email protected]
Subject
RE: st: RE: Poisson Regression
Date
Tue, 15 Feb 2011 02:19:39 -0800 (PST)
Thanks for considerations! I did mencion that is cross sectional study. Tha'ts no problem, right?
Greetings, Alexandra
--- Em ter, 15/2/11, Maarten buis <[email protected]> escreveu:
> De: Maarten buis <[email protected]>
> Assunto: RE: st: RE: Poisson Regression
> Para: [email protected]
> Data: Terça-feira, 15 de Fevereiro de 2011, 8:26
> --- Visintainer, Paul wrote:
> > My frustration is that when the outcome is common and
> > logistic regression is used, there virtually no
> discussion
> > of clinical relevance -- only statistical
> significance,
> > (e.g., is a significant odds ratio of 2.5 clinically
> > relevant? Perhaps if the base risk is 2%; perhaps
> not
> > if the base risk 73%.
>
> This is where Stata has a problem: it automatically
> suppresses
> the display of the baseline odds when you ask for odds
> ratios
> (and baseline hazard when you ask for hazard ratios, and
> baseline incidence rate when you ask for incidence rate
> ratios,
> etc.).
>
> To me the baseline odds serve two purposes:
>
> First, is it really helps in communicating the results. By
>
> discussing it first in the results section of a paper you
> refresh the readers memory on what an odds is. It also
> makes
> the model less "magical" if you frame it in number of high
>
> status jobs, deaths, or successes per low status job,
> survivals,
> or failures. You frame the model in terms that the reader
> care
> about.
>
> Second, it helps when trying to determine the size of of an
>
> effect. An odds ratio of 2 is not very impressive if the
> baseline
> odds is small 2 times a small number is still a small
> number,
> while is much more impressive if the baseline odds is
> large.
> Alternatively, if your baseline odds is already 50
> successes per
> failure, then any increase is not going to have much
> substantive
> meaning.
>
> There is a trick you can use to display the baseline odds,
> which
> is discussed in a slighly different context 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>
>
>
> -- Maarten
>
> Ps. those who have followed the list a while will have
> noticed that
> I made this point before. I hope I did not bore them too
> much.
>
> --------------------------
> Maarten L. Buis
> Institut fuer Soziologie
> Universitaet Tuebingen
> Wilhelmstrasse 36
> 72074 Tuebingen
> Germany
>
> http://www.maartenbuis.nl
> --------------------------
>
>
>
>
>
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