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An Investigation of Ordinal True Score Test TheoryEducational Testing Service
University of Southern California
The validity of the assumptions underlying Cliff's (1989) ordinal true score theory (OTST) were investigated in a three-stage study. OTST makes only ordinal assumptions about the data, and provides a means of converting ordinal item information into summary ordinal information about examinees. Stage 1 was a simulation based on a classical (weak true score) test theory model. Stage 2 used a long empirical test to approximate the true order. Stage 3 was an extensive simulation based on the three-parameter logistic model. The results of all three studies were consistent; the assumption of local ordinal uncorrelatedness was violated in that partial item-item gamma (y) cor relations were positive instead of 0. The assump tion of proportional distribution of ties was violatedpairs tied on one item were not distributed on the other as prescribed. The item- true order tau (
Key Words: Index terms: classical test theory item response models local independence monte carlo simulation nonparametric test models ordinal regression ordinal test models, test theory.
Applied Psychological Measurement, Vol. 15, No. 4,
335-351 (1991) This article has been cited by other articles:
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) correlation was consistently overestimated, although the estimated 