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The Effects of Dimensionality on Equating the Law School Admission Test
Author(s) -
Camilli Gregory,
Wang Mingmei,
Fesq Jacqueline
Publication year - 1995
Publication title -
journal of educational measurement
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.917
H-Index - 47
eISSN - 1745-3984
pISSN - 0022-0655
DOI - 10.1111/j.1745-3984.1995.tb00457.x
Subject(s) - equating , item response theory , curse of dimensionality , test (biology) , set (abstract data type) , statistics , mathematics , item analysis , deductive reasoning , psychology , econometrics , psychometrics , computer science , artificial intelligence , paleontology , rasch model , biology , programming language
Using factor analysis, we conducted an assessment of multidimensionality for 6 forms of the Law School Admission Test (LSAT) and found 2 subgroups of items or factors for each of the 6 forms. The main conclusion of the factor analysis component of this study was that the LSAT appears to measure 2 different reasoning abilities: inductive and deductive. The technique of N. J. Dorans & N. M. Kingston (1985) was used to examine the effect of dimensionality on equating. We began by calibrating (with item response theory [IRT] methods) all items on a form to obtain Set I of estimated IRT item parameters. Next, the test was divided into 2 homogeneous subgroups of items, each having been determined to represent a different ability (i.e., inductive or deductive reasoning). The items within these subgroups were then recalibrated separately to obtain item parameter estimates, and then combined into Set II. The estimated item parameters and true‐score equating tables for Sets I and II corresponded closely.