This study examined some effects of using a unidimensional
IRT model when the assumption of unidimensionality
was violated. Adaptive and nonadaptive
tests were formed from two-dimensional item sets.
The tests were administered to simulated examinee
populations with different correlations of the two underlying
abilities. Scores from the adaptive tests
tended to be related to one or the other ability rather
than to a composite. Similar but less disparate results were obtained with IRT scoring of nonadaptive tests,
whereas the conventional standardized number-correct
score was equally related to both abilities. Differences
in item selection from the adaptive administration and
in item parameter estimation were also examined and
related to differences in ability estimation. Index
terms: ability estimation, adaptive testing, item parameter
estimation, item response theory, multidimensionality.
Folk, Valerie G & Green, Bert F. (1989). Adaptive estimation when the unidimensionality assumption of IRT is violated. Applied Psychological Measurement, 13, 373-389. doi:10.1177/014662168901300404
Folk, Valerie G.; Green, Bert F..
Adaptive estimation when the unidimensionality assumption of IRT is violated.
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