The extent to which three appropriateness
indexes-Z, ECIZ₄, and W (a variation of Wright’s
person-fit statistic)-are well-standardized was
investigated in a monte carlo study. To assess the
effects of the item response theory (IRT.) model and
test length on the distribution of the indexes and
their cutoff values at three false positive rates,
nonaberrant response patterns were generated.
ECIZ₄ most closely approximated a normal
distribution, showing less skewness and kurtosis
than Z, and W. The ECIZ₄ cutoff values were
affected less by test length and the IRT model than
were Z, and W. In contrast, the distribution of W
was the least stable over replications, and its cutoff
values varied greatly depending on the IRT model
and test length. Index terms: appropriateness
measurement, caution index, item response theory
(person fit), person-fit statistics, unusual response
Noonan, Brian W, Boss, Marvin W & Gessaroli, Marc E. (1992). The effect of test length and IRT model on the distribution and stability of three appropriateness indexes. Applied Psychological Measurement, 16, 345-352. doi:10.1177/014662169201600405
Noonan, Brian W.; Boss, Marvin W.; Gessaroli, Marc E..
The effect of test length and IRT model on the distribution and stability of three appropriateness indexes.
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