DEVELOPMENT AND EVALUATION OF A MIXED APPROACH USING THE LOGISTIC LATENT CLASS MODEL AND THINK-ALOUD PROTOCOLS TO INFORM DIFFERENTIAL ITEM FUNCTIONING
Open Access
Author:
Yu, Lan
Graduate Program:
Educational Psychology
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
May 02, 2007
Committee Members:
Hoi Kin Suen, Committee Chair/Co-Chair Pui Wa Lei, Committee Member Jonna Marie Kulikowich, Committee Member Aleksandra B Slavkovic, Committee Member Dorothy H Evensen, Committee Member
Keywords:
differential item functioning mixture model think-aloud protocols
Abstract:
As an indicator of group difference at the item level, differential item functioning (DIF) is a commonly used method with two major limitations. One is that DIF results and sensitivity review results may not be consistent which results in failure to explain the performance differences between groups. The second limitation is that the grouping variable used in DIF is often arbitrarily chosen, which may not be the primary factor associated with group performance difference. This study proposes a mixed approach using the logistic latent class (LLC) model and think-aloud verbal protocols to inform DIF analysis. Specifically, the LLC model is used to identify underlying latent classes based on examinees’ item response patterns and the think-aloud verbal protocol analysis is used to capture different thinking processes associated with different latent classes. DIF results are compared before and after latent class has been controlled for. A sample of 3, 000 students taking the 60-item English placement test is used for the LLC and DIF analyses. A stratified sample of 30 students is used for think-aloud verbal protocol analysis. The LLC model shows its usefulness in understanding how DIF occurs and in guiding sensitivity review. But the think-aloud verbal protocol analysis does not support the association between different thinking processes and different latent classes. Limitations and future research of this mixed approach are further discussed.
