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From |
Arne Risa Hole <arnehole@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: asclogit or clogit or mixlogit |

Date |
Thu, 4 Jun 2009 13:33:01 +0100 |

Hi Shehzad, Your -clogit- model can be estimated using -asclogit- as follows: bysort choiceset: gen alt = _n asclogit choice frequency relief cost, case(choiceset) alt(alt) noconst Look up the definition of the -alternatives()- option of -asclogit- in the Stata manual. To capture preference heterogeneity in terms of the observable characteristics of the decision-makers you need to interact them with the alternative attributes. It makes no sense to include them as covariates using the -casevars()- option since your alternatives are unlabelled (what does it mean that female respondents have a greater tendency to choose alternative A, for instance?) -mixlogit- is a version of -asclogit- that allows the coefficients to be random, whether you want this or not depends on the goal of your research project. Arne 2009/6/3 Shehzad Ali <drshehzad_ali@yahoo.com>: > Hi listers, > > I am analysing a discrete choice experiment in which 100 individuals are asked about their treatment preference for pain relief. Each individual is offered 10 choice sets, each with two alternatives (A and B); each alternative has 3 attributes (frequency of treatment [frequency], duration of pain relief [relief] and cost [cost]). A typical choice set would look like this: > > Choice set # 1 > > Alternative A: > frequency of treatment (per day) = 3 > duration of pain relief (in hours) = 8 > cost ($) = 1 > > Alternative B: > frequency of treatment (per day) = 2 > duration of pain relief (in hours) = 12 > cost ($) = 1.5 > > I also have individual level characteristics including age, sex, education and income. The data is in long table form; so I have 100 x 10 x 2 = 2,000 observations. The data is organised such that: > > id = remains the same for each individual, i.e. for each set of 20 observations > choice = 0/1 dummy for choice made in each choice set > choiceset = same for the two alternatives in each choice set, i.e. there are 1,000 choicesets numbered from 1 to 1,000 > > I was using the conditional logit model below: > > clogit choice frequency relief cost, group(choiceset) > > Can anyone suggest whether using an -asclogit- or -mixlogit- be more appropriate in this situation, especially if I wish to take account of individual characteristics (I understand the other way would be to use interaction terms in -clogit-)? Also can you suggest the appropriate syntax for using -asclogit- and -mixlogit- in this situation (when I tried using: [asclogit choice frequency relief cost, casevars (age sex education income) case(id) alternatives(choiceset)], I get the error: variable choiceset has replicate levels for one or more cases). > > Any help would be greatly appreciated. > Thank you, > Shehzad > > > > > * > * 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/ > * * 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/

**References**:**st: asclogit or clogit or mixlogit***From:*Shehzad Ali <drshehzad_ali@yahoo.com>

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