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

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Calculating and interpreting effect size when DV is a proportion |

Date |
Mon, 14 Jan 2013 09:42:27 +0100 |

--- On Sat, Jan 12, 2013 at 7:50 PM, Michelle Dynes >> I am conducting analyses using proportion data as my outcome. I am >> using GLM with a logit link and the binomial family to carry out the >> analyses. I would like to determine the effect size of my independent >> variables. Here are two options I have considered: >> >> Generate Odds Ratios using the -eform- command at the end of the GLM >> statement. Does this make sense to do when my outcome is not >> dichotomous? On Mon, Jan 14, 2013 at 7:41 AM, Jeffrey Wooldridge wrote: > I would use the "margins" command to compute the average marginal > effects. That we you do not have to fix the explanatory variables > (continuous or binary) at any specific values. For the binary > variables, you get the change in the predicted y when the dichotomous > variable goes from zero to one. For the continous variables you get > the effect of a one-unit increase in x (provided that is a reasonable > change and the calculus approximation is sensible). You can also use the exponentiated coefficients, but they are not odds ratios. In the past I have called these "relative proportion ratios". The interpretation of these numbers is exactly the same as in -betafit- and in the helpfile of -betafit- there is a discussion of these coefficients. You can install -betafit- (and thus obtain its helpfile) by typing in Stata: -ssc install betafit-. I have also applied this logic to a fractional logit model in this post on Statalist: <http://www.stata.com/statalist/archive/2013-01/msg00011.html>. Hope this helps, Maarten Ps. I hope Michelle has also included the -vce(robust)- option to her -glm- command. This is a crucial part of the fractional logit model. --------------------------------- 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: Calculating and interpreting effect size when DV is a proportion***From:*Michelle Dynes <dynes.michelle@gmail.com>

**st: manipulating chains of data***From:*Dalhia <ggs_da@yahoo.com>

**References**:**st: Calculating and interpreting effect size when DV is a proportion***From:*Michelle Dynes <dynes.michelle@gmail.com>

**Re: st: Calculating and interpreting effect size when DV is a proportion***From:*Jeffrey Wooldridge <jmwooldridge60@gmail.com>

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