Jean-Benoit,
merci! That's a very thorough explanation. I've no doubts that I have
a small sample problem whichever way you will turn it. I tried Rasch
model with -xtlogit- (or -xtmelogit-), and the results were
essentially a slightly curved version of the total number correct.
One clarification: you said,
> I suppose you have too an other problem which is the violation of the
> local independence assumption: in IRT, conditionnaly to the latent
> variable, the responses to the items must be independent. You say that
> there is items with a little number of negative (incorrect) responses,
> and the phenomenon can create a violation of this assumption. Testing
> the fit of a Mokken scale (non parametric IRT model) can detect such a
> violation. This model can be fit with the -loevH- command (available on
> SSC) [I can send you a paper submit to the Stata Journal which explain
> the outputs of this command].
If those are just difficult problems, then I should expect only the
top students to answer them. Why does this create violation of local
independence?
--
Stas Kolenikov, also found at http://stas.kolenikov.name
Small print: I use this email account for mailing lists only.
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