Hello all,

I have scoured the internet for answers, and downloaded several packages in Stata to no success. I am hoping that someone may be able to guide me on this.

I am analyzing a 40 item survey instrument using a modified 4-point Likert scale. I have been conducting item response theory analyses using irt grm. I need to conduct differential item functioning (dif) between two groups. I have tried to use the diflogistic command, but get an error that data must be missing, 0, or 1. I have tried using uirt, but get errors here too.

I saw a post on this from 2018 without any answers. Could anyone help me with conducting dif on ordinal items in Stata?

Thank you so much in advance!

Elle