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Re: st: use of rologit
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
________________________
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[email protected]
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