DIFAS

Author: Randall D. Penfield
Contact: http://soe.uncg.edu/academics/departments/erm/erm-software/
Description: DIFAS: Differential Item Functioning Analysis System. Windows-based program that computes odds ratio estimates of differential item functioning, differential test functioning, and differential step functioning effects, along with associated tests of significance. This includes the Mantel-Haenszel common log-odds ratio, the Breslow-Day test of trend in odds ratio heterogenity, and Liu-Agresti cumulative common log-odds ratio, and the relevant generalizations to step-level analyses for polytomous items.
Analyses: Item & Test Analysis; Latent Class Models; Multilevel Data
System Requirements: Windows
Measurement Model: IRT/Rasch
License Type: Freeware
Documentation: A manual is available in PDF format free of charge