SIMEX-Based and Analytical Bias Corrections in Stocking–Lord Linking

Abstract

Stocking–Lord (SL) linking is a popular linking method for group comparisons based on dichotomous item responses. This article proposes a bias correction technique based on the simulation extrapolation (SIMEX) method for SL linking in the 2PL model in the presence of uniform differential item functioning (DIF). The SIMEX-based method is compared to the analytical bias correction methods of SL linking. It turned out in a simulation study that SIMEX-based SL linking performed best, is easy to implement, and can be adapted to other linking methods straightforwardly.

Keywords

• Stocking–Lord linking
• SIMEX
• item response model
• linking
• 2PL model
• bias correction