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Topics - KatharinaBorg

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Questions and Answers / Differential Item Functioning
« on: October 30, 2013, 03:53:25 PM »

I am calculating DIF analyses with dichotomous items from TIMSS comparing two German versions of the test to identify a set of anchor items for further research.
The manual describes quite well how to formulate the model statement and how to interpret the output, but due to the fact that I am writing a statistics thesis I am furthermore interested in details about the applied mathematical models and test statistics.

Concretely, I would be glad to get some reference papers to

a)   the underlying assumptions and model specifications when computing “model item – dif.variable + item*dif.variable”
b)   the computed “Chi-square test of parameter equality” (e.g., ConQuest Manual, Figure 8-2)
c)   test specifications for the ESTIMATE values for the item*dif.variable term (ConQuest Manual, Figure 8-2, TERM 3)
[Of special interest would be a reference proving that “If zero is not element of [ESTIMATE – 2*ERROR; ESTIMATE + 2*ERROR] it is an indicator for the existence of DIF”.]

Thanks and best wishes,

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