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From |
Maarten Buis <maartenlbuis@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: xtlogit, margins |

Date |
Thu, 8 Nov 2012 13:36:15 +0100 |

On Wed, Nov 7, 2012 at 3:03 PM, JVerkuilen wrote: > There are some reasons to suppose that log-odds is better perceived > than odds ratios or probabilities because they concatenate in a way > that is psychophysically coherent, that is they add linearly. To me an effect is just a comparison of groups (*). Such a comparison can be done be computing a difference or a ratio. You can say group A earns on average x euros/dollars/yen/pounds/... more than group B (effect as a difference) or you can say group A earns on average y% more than group B (effect as a ratio). I don't understand why one statement would be more coherent than the other. > The odds ratio makes sense as an approximation of relative risk > so that's useful when the relative risk is desirable. This misconception is the source of many errors. The safest thing is to interpret odds ratios as odds ratios and risk ratios as risk ratios and not try to see one as an approximation of the other. The approximation only applies under special circumstances, and too often people just conveniently forget that. If you want relative risk you should estimate a model that return relative risks (-poisson-). -- Maarten (*) in case of a continuous variable the number of groups is very large, but the principle remains the same. --------------------------------- Maarten L. Buis WZB Reichpietschufer 50 10785 Berlin Germany http://www.maartenbuis.nl --------------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: xtlogit, margins***From:*"JVerkuilen (Gmail)" <jvverkuilen@gmail.com>

**References**:**st: xtlogit, margins***From:*"Seliger Florian" <seliger@kof.ethz.ch>

**Re: st: xtlogit, margins***From:*Maarten Buis <maartenlbuis@gmail.com>

**AW: st: xtlogit, margins***From:*"Seliger Florian" <seliger@kof.ethz.ch>

**Re: st: xtlogit, margins***From:*Maarten Buis <maartenlbuis@gmail.com>

**Re: st: xtlogit, margins***From:*Austin Nichols <austinnichols@gmail.com>

**Re: st: xtlogit, margins***From:*"JVerkuilen (Gmail)" <jvverkuilen@gmail.com>

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