Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: IIA violations and subsequent steps


From   Douglas Garrett <d.garrett@utoronto.ca>
To   statalist@hsphsun2.harvard.edu
Subject   st: IIA violations and subsequent steps
Date   Sun, 05 Aug 2007 17:35:35 -0400

Hello!
I am currently running a multinomial logistic regression model and have found that it violates the IIA assumption. Of course, one option in this case is to fit a nested logit model to these data to allow error terms to correlate within parent-levels of the nested structure. However, all of my predictors describe characteristics of participants rather than of choices. To my understanding, this person-level type of predictor is not appropriate for a nested logit model, as predictors are required typically that vary along with the choices themselves. If that is correct then, how does one handle IIA violations in a multinomial logistic model with predictors that are choice-invariant? Might there be a work-around to allow error terms of certain choices to correlate prior to running a multinomial model such as this?

Many thanks in advance.



Douglas Garrett
Grady Lab
Rotman Research Institute
Baycrest
Department of Psychology
University of Toronto






*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/




© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index