Open AccessCLUSTERS AS THE UNIT OF ANALYSIS IN DIFFERENTIAL ITEM FUNCTIONING
Author(s) -
Bennett Randy Elliot,
Rock Donald A.,
Novatkoski Inge
Publication year - 1988
Publication title -
ets research report series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.235
H-Index - 5
ISSN - 2330-8516
DOI - 10.1002/j.2330-8516.1988.tb00326.x
Subject(s) - differential item functioning , cluster (spacecraft) , differential (mechanical device) , psychology , cognitive psychology , item response theory , developmental psychology , psychometrics , computer science , engineering , programming language , aerospace engineering
ABSTRACT This study developed, applied, and evaluated a theory‐based method of detecting the underlying causes of differential difficulty. The method was intended to improve on traditional approaches that too often produce uninterpretable results. Key elements of the method were the analysis of item clusters and the incorporation of theoretical predictions about cluster performance. The method was applied in two subgroups taking SAT‐M and involved (1) reviewing literature syntheses to identify factors that might cause differential item functioning, (2) forming item categories based on those factors, (3) identifying categories that functioned differentially, (4) assessing the functioning of the items composing deviant categories, and (5) relating item and category functioning. Results were compared to a traditional item‐level analysis. In both subgroups, the cluster and traditional methods agreed on the overall extent of differential functioning (substantial in the first group, virtually absent in the second). Additionally, the pattern of differential functioning detected was interpretable. At the same time, several important limitations were apparent. The method would seem to be applied most productively when a small number of hypotheses can be derived from a reasonably strong research base, overlap among cluster structures can be avoided, and results can be supplemented with experimental studies or protocol analyses.