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Re: st: poisson vs. ologit for pinprick data

From   "Clive Nicholas" <>
Subject   Re: st: poisson vs. ologit for pinprick data
Date   Sat, 6 Dec 2003 23:20:15 -0000 (GMT)


The ordered logit approach seems more appropriate here than does Poisson.
The latter is intended to model events, of which the independence between
them is moot. -ologit- also appears to be appropriate since your response
variable is indeed ordered, but not interval (and, reading between the
lines of your post, is measured only once).

The variance being greater than the mean value appears to be neither here
nor there: all that is telling you is that there is a lot of unexplained
variation in your sample (how large is it, out of interest?), which your
independent variables may or may not account for.

Hope that helps! :-)


Tim Wade wrote:

> Dear Statalisters:
> I've been off this list for a while and am greatly
> enjoying my return to this excellent resource and
> community.
> I'm seeking advise for the appropriate model for
> pinprick data scaled from 1 to 5 where 1 represents
> the most sensitive and 5 the least to the pinprick
> stimulus. I need to model this as a function of
> several dependent variables. The pinprick data are
> distributed something like Poisson, but the variance
> is considerably less than the mean (mean=1.28,
> var=0.52), and it does not seem to be a real "count"
> type of outcome. Could a poisson model be appropriate
> here? Or an ordered logit? Any other suggestions?
> Thanks very much.

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