Robustness of item parameter estimation programs to assumptions of unidimensionality and normality

Citation
L. Kirisci et al., Robustness of item parameter estimation programs to assumptions of unidimensionality and normality, APPL PSYC M, 25(2), 2001, pp. 146-162
Citations number
69
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Psycology
Journal title
APPLIED PSYCHOLOGICAL MEASUREMENT
ISSN journal
0146-6216 → ACNP
Volume
25
Issue
2
Year of publication
2001
Pages
146 - 162
Database
ISI
SICI code
0146-6216(200106)25:2<146:ROIPEP>2.0.ZU;2-8
Abstract
The effects of test dimensionality (one- or three-dimensional), theta distr ibution shape (normal, positively skewed, or platykurtic), and estimation p rogram (BILOG, MULTILOG, or XCALIBRE) on the accuracy of item and person pa rameter estimates were assessed. The criterion was the root mean squared er ror of the difference between estimated and true parameter values. There wa s an interaction between program and dimensionality, indicating that the ro bustness of the unidimensionality assumption was a function of the estimati on program. With the sample size and test length used, unidimensional estim ation programs were insensitive to different shapes of the underlying theta distribution. BILOG consistently produced the smallest root mean squared e rror under most conditions. However, MULTILOG and XCALIBRE showed less vari ance in parameter estimation due to the violation of unidimensionality, wit h the exception of estimating the discrimination parameter in MULTILOG. Gui delines for estimating parameters of multidimensional test items using unid imensional item response theory models are suggested.