H. Wainer, PRECISION AND DIFFERENTIAL ITEM FUNCTIONING ON A TESTLET-BASED TEST -THE 1991 LAW-SCHOOL ADMISSIONS TEST AS AN EXAMPLE, Applied measurement in education, 8(2), 1995, pp. 157-186
Citations number
48
Categorie Soggetti
Psychology, Educational","Psychologym Experimental","Education & Educational Research
Two components of the Law School Admissions Test (LSAT)-reading compre
hension and analytic reasoning-are not constructed of individual items
that can function autonomously. Instead they each consist of four clu
sters of items, in which each cluster refers to a common stem. In read
ing comprehension the common part is a single passage; in analytic rea
soning it is a common situation. Such interdependent clusters of items
have come to be called testlets. It has been found that when a test i
s constructed of testlets, traditional treatments of individual items
as independent entities tends to yield overly optimistic estimates of
reliability. It has also been found that even though individual items
may pass muster in terms of their differential performance within vari
ous subgroups, this may not be true once the items within a testlet ar
e treated as a coherent unit. Findings can be divided into three categ
ories: (a) overall performance of individual subgroups on the test, (b
) the reliability of each section, and (c) the differential performanc
e of items/testlets. This article describes these findings and provide
s the details of the methods used in the investigation.