Caribbean Journal of Psychology: Vol. 4, Issue 1, 2011

Article 3
Using IRT-DIF Methodology in Detecting and Evaluating Brief Symptom Inventory Item Response Differences among Afro-Caribbean and European Adults

David Lee Mount
Wake Forest University Health Sciences

Michael Canute Lambert
The University of North Carolina at Chapel Hill

Cecilia A. Essau
Rohampton University

Maureen E. Samms-Vaughan
University of the West Indies, Mona Campus

Anna Bokszczanin
Opole University



Abstract

The current study used Item Response Theory to investigate item level information from the Brief Symptom Inventory (BSI), a 53-item self-report instrument developed to measure psychological distress in nine areas of mental health functioning. Focusing on non-psychiatric-service-connected white Europeans (n = 347) and Afro-Caribbean adults (n = 431), the findings revealed unidimensionality for five of nine BSI factors. Analyses of the unidimensional factors revealed: (a) variance (i.e., differential item functioning) in how well a few items discriminated cross-regionally; (b) variance in estimating severity levels in adults with identical psychological distress cross-regionally; and (c) that items measured different psychological distress levels. Results suggest that addressing psychometric variance and using IRT-based scoring might yield more accurate BSI measurement information.