Open AccessDIFFERENTIAL TESTLET FUNCTIONING DEFINITIONS AND DETECTION
Author(s) -
Wainer Howard,
Sireci Stephen G.,
Thissen David
Publication year - 1991
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.2333-8504.1991.tb01388.x
Subject(s) - psychology , item response theory , parallels , differential item functioning , test (biology) , statistics , differential (mechanical device) , econometrics , psychometrics , mathematics , developmental psychology , mechanical engineering , paleontology , engineering , biology , aerospace engineering
It is sometimes sensible to think of the fundamental unit of test construction as being larger than an individual item. This unit, dubbed the testlet, must pass muster in the same way that items do. One criterion of a good item is the absence of DIF—the item must function in the same way in all important subpopulations of examinees. In this paper we define what we mean by testlet DIF and provide a statistical methodology to detect it. This methodology parallels the IRT‐based likelihood ratio procedures explored previously by Thissen, Steinberg & Wainer (1988, in press). We illustrate this methodology with analyses of data from a testlet‐based experimental version of the Scholastic Aptitude Test.