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From |
"Data Analytics Corp." <dataanalytics@earthlink.net> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: use of rologit |

Date |
Fri, 22 Aug 2008 11:31:31 -0400 |

Hi, Thanks for the clues. I'll look for elogit. Thanks, Walt Phil Schumm wrote:

On Aug 21, 2008, at 7:40 PM, Data Analytics Corp. wrote:A potential client asked for a form of analysis sometimes done in market research called maximum-difference (maxdiff) analysis. Basically, consumers are presented with a series of product attributes (say, four at a time or a "quad") and then are asked to select the one they prefer the most and the one they prefer the least. For a quad, the other two non-selected attributes just fall in the middle. This is repeated several times with the attributes rotating following an experimental design. Since the attributes are rated, I was thinking of using rologit to estimate a model. But then I found a statement in the reference manual that says that "rologit does not allow for other forms of incompleteness, for instance, data in which respondents indicate which of four cars they like best, and which one they like least, but not how they rank the two intermediate cars." But this is exactly my problem. Does anyone know how to trick rologit, or know of an ado file to handle this problem?

The rank ordered logit model may also be fit using -stcox-. Allison and Christakis [1] show how this approach can be generalized to handle the types of ties you describe above. Also, Jeroen Weesie wrote a Stata command many years ago called -elogit- to fit this model (try -findit elogit-) -- I can't recall though how he handled the subject of ties.

-- Phil

[1] P. D. Allison and N. A. Christakis. Logit models for sets of ranked items. Sociological Methodology, 24:199–228, 1994.

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-- ________________________ Walter R. Paczkowski, Ph.D. Data Analytics Corp. 44 Hamilton Lane Plainsboro, NJ 08536 ________________________ (V) 609-936-8999 (F) 609-936-3733 dataanalytics@earthlink.net www.dataanalyticscorp.com * * 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: use of rologit***From:*"Data Analytics Corp." <dataanalytics@earthlink.net>

**Re: st: use of rologit***From:*Phil Schumm <pschumm@uchicago.edu>

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