An alternative approach for item response theory
observed-score equating is described. The number-correct
score distributions needed in equating are found
by numerical integration over the theoretical or empirical
distributions of examinees’ traits. The item response
theory true-score equating method and the observed-score
equating method described by Lord, in which the
number-correct score distributions are summed over a
sample of trait estimates, are compared in a real test
example. In a computer simulation, the observed-score
equating methods based on numerical integration and
summation were compared using data generated from
standard normal and skewed populations. The method
based on numerical integration was found to be less
biased, especially at the two ends of the score distribution.
This method can be implemented without the need
to estimate trait level for individual examinees, and it is
less computationally intensive than the method based on
summation. Index terms: equating, item response
theory, numerical integration, observed-score equating.
Zeng, Lingjia & Kolen, Michael J. (1995). An alternative approach for IRT observed-score equating of number-correct scores. Applied Psychological Measurement, 19, 231-240. doi:10.1177/014662169501900302
Zeng, Lingjia; Kolen, Michael J..
An alternative approach for IRT observed-score equating of number-correct scores.
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