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From |
Klaus Pforr <kpforr@googlemail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: clogit for discrete choice experiment with multiple choice sets |

Date |
Mon, 30 Jan 2012 10:36:03 +0100 |

<> Dear Hadji,

xp choice 1 1 2 2 3 3

Permutaion Was it chosen? 123 yes 132 no 213 no 231 no 312 no 321 no

Here is the literature:

I hope this helps best Klaus Am 28.01.2012 08:32, schrieb Hadji Cortez Jalotjot:

Hi! I implemented a discrete choice experiment to model vehicle choice. In my questionnaire, I presented each respondents with 10 choice experiments or choice sets with each choice set having 3 alternatives or choices. The explanatory variables are the characteristics of the vehicles. With this, I am fitting a conditional logit model. In my data set, dummy variables were used to represent the explanatory variables. Since each choice experiment has 3 alternative options, each choice experiment corresponds to 3 rows of observations. So 10 choice experiments per respondent X 3 alternative options per choice experiments = 30 rows of observations per respondent. (sample data below shows only 3 choice experiments with some of the explanatory variables for respondent 1) respno choice_set choice var1a var1b var1c .. . .. none 1 1 1 1 0 0 0 1 1 0 0 0 1 0 1 1 0 0 0 0 1 1 2 0 0 1 0 0 1 2 1 1 0 0 0 1 2 0 0 0 0 1 1 3 0 0 0 1 0 1 3 0 1 0 0 0 1 3 1 0 0 0 1 For clogit to work, I must select a variable that will identify the grouping for which the software will run the analysis. Now, for this kind of data in which respondents answered multiple choice sets (10 in my case), which should I used as a group? Is it the respno or choice_set? I am confused because if I use respno, Stata says multiple positve outcomes in a group. And the predicted probabilities is computed for the whole 30 alternative options and not only for the 3 alternative options per choice set. But if I use the choice_set as the grouping and I extend the model to include respondent characteristics (e.g. income), I may have problem with fixed effects because for example choice_set 1 and choice_set 2 is from the same respondent and therefore will have exactly the same income. Any advice is appreciated. Hadji * * 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/

-- __________________________________ Klaus Pforr MZES AB - A Universität Mannheim D - 68131 Mannheim Tel: +49-621-181 2797 fax: +49-621-181 2803 URL: http://www.mzes.uni-mannheim.de Besucheranschrift: A5, Raum A309 __________________________________ * * 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: clogit for discrete choice experiment with multiple choice sets***From:*Klaus Pforr <kpforr@googlemail.com>

**Re: st: clogit for discrete choice experiment with multiple choice sets***From:*Nick Cox <njcoxstata@gmail.com>

**References**:**st: clogit for discrete choice experiment with multiple choice sets***From:*Hadji Cortez Jalotjot <jalotjot@yahoo.com>

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