Author Topic: Different item estimates across models?  (Read 506 times)

Georg II

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Different item estimates across models?
« on: January 17, 2017, 05:42:54 PM »
Dear colleagues,

I’d be thankful if you replied this question.
I separately fitted two models to a data set: a unidimensional and a within-item two dimensional model. The item difficulty estimates of the items which simultaneously load on a second dimension in the two-dimensional model differ noticeably from the values they have in the unidimensional model. The items which load on only one dimension have the same estimates across the two analyses. What does this mean?
Thanks for your help

Alvin Vista

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Re: Different item estimates across models?
« Reply #1 on: January 29, 2017, 10:42:14 PM »
Hi Georg,
This could be due to either of your models not fitting the data properly, or if the fit differs drastically between your models.
You can get more information on fitting multidimensional models in the link below: