Multidimensional IRT and DIF in R with mirt

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For rcode and dataset: https://gist.github.com/musa5237

Tutorial video of how to run the Multidimensional Item Response Theory (MIRT) and detect Differential Item Functioning (i.e., bias items) for ordinal polytomous response data in R. Packages used are mirt. The model used was the multidimensional extension of the Graded Response Model (GRM).
Confirmatory, exploratory, and bifactor models were reviewed. In addition, DIF with anchor items was reviewed.
Discussion board for questions related to the package where I received help: https://groups.google.com/g/mirt-package
Dataset was responses to the Generic Conspiracist Beliefs Scale (GCBS; Brotherton, French, and Pickering, 2013). The instrument is designed to measure degree of conspiracy theory beliefs. The goal was to measure the psychometric properties of the instrument and detect items in the instrument that may be more biased toward one gender.