Comparing Four Lower Bound Coefficients of Reliability Under Violation of the Assumption of Unidimensionality

• In Event: Reliability and Subscores

Abstract

This study examined how the dimensionality of a test influences the values of four lower bound estimates of reliability: coefficient alpha, Lambda2, Feldt-Gilmer coefficient and Feldt's coefficient by comparing bias in these four coefficients through simulated data. The results revealed that the increase of dimensionality and heterogeneity of items on different dimensions cause larger bias in these estimates. Among the four coefficients, FG coefficient had substantially lower bias, thus the best estimate of reliability in this study.

Authors

• Wei Tang, University of Alberta

• Ying Cui, University of Alberta