IRT modeling doesn't care much whether an item is free response or not, just the scale on which it's scored. Binary and polytomous scoring = IRT model. Continuous scoring = Factor analysis.
If by mentioning free response, you mean students are unlikely to guess the correct answer, even when they don't know it, it's a 2 parameter IRT rather than 3.
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IRT modeling doesn't care much whether an item is free response or not, just the scale on which it's scored. Binary and polytomous scoring = IRT model. Continuous scoring = Factor analysis.
If by mentioning free response, you mean students are unlikely to guess the correct answer, even when they don't know it, it's a 2 parameter IRT rather than 3.
Best of luck! :)