This (unidimensional) dataset includes item parameters for two groups estimated under the three parameter logistic model, the generalized partial credit model, and the nominal response model. There are 15 common items (7 drm, 3 gpcm, 5 nrm). This dataset is for illustrative purposes to show how items from different response models can be mixed together and common items can be in different positions across groups.
A list of length four. The first element is a list of length two with item parameter estimates for groups 1 and 2 respectively. The gpcm items do not include a location parameter. The second list element is a list identifying the number of response categories for the two groups. The third element, specifies which items correspond to the different item response models for each group respectively. The last element is a matrix of common items between the two groups.
The item parameters are loosely based on parameters listed in the following articles
Kim, J.-S. (2006). Using the Distractor Categories of Multiple-Choice Items to Improve IRT Linking. Journal of Educational Measurement, 43(3), 193-213.
Kim, S. & Lee, W.-C. (2006). An Extension of Four IRT Linking Methods for Mixed-Format Tests. Journal of Educational Measurement, 43(1), 53-76.
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