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

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Binary Choice Model and fixed effects - interpreting the interaction effects? |

Date |
Mon, 2 Apr 2012 12:10:55 +0200 |

On Mon, Apr 2, 2012 at 11:57 AM, Benjamin Niug wrote: > I want to estimate a binary choice model accunting for time-invariant > fixed effects (I read I could use the -xtlogit- or -clogit- command). > > y_it = b_1*x_1_it*x_2_it+b_2*x_1_it + b_3*x_2_it > > However, I have included an interaction effect which I want to > interpret correctly - as pointed out by Ai and Norton (2004) this is > not trivial. They suggest to use a user written command called > -inteff-. This command works well if -logit- is used, however, it does > not work if -xtlogit- or -clogit- is used. Please note that just author-year references are not appreciated on this list. Please give the complete reference. This is discussed on the Statalist FAQ. The logic is that this is a multi-disciplinary list. Even if a citation is so famous within your (sub-(sub-)discipline that author-year suffices, this is likely not to be the case for the rest of the world. However, often many disciplines will have independently faced (and solved) the same problem, and they have something useful to say about the subject. You have a double problem here: a) interpreting marginal effects of interaction terms is hard, and b) interpreting marginal effects in multi-level/panel/fixed effects models is hard. So the combination of the two means that that is going to be very hard. However, the solution is simple: don't do marginal effects but interpret your coefficients in the natural metric of the model. In this case the odds of success. Odds, odds ratios and ratios of odds ratios have an undeserved reputation of being hard to interpret. You can see an example of how easy that is here in: M.L. Buis (2010) "Stata tip 87: Interpretation of interactions in non-linear models", The Stata Journal, 10(2), pp. 305-308. Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: Binary Choice Model and fixed effects - interpreting the interaction effects?***From:*Benjamin Niug <benjamin.niug@googlemail.com>

**References**:**st: Binary Choice Model and fixed effects - interpreting the interaction effects?***From:*Benjamin Niug <benjamin.niug@googlemail.com>

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