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Browsing by Author "Harris, Deborah J."

Now showing 1 - 3 of 3
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    An application of the three-parameter IRT model to vertical equating
    (1987) Harris, Deborah J.; Hoover, H. D.
    This study examined the effectiveness of the three-parameter IRT model in vertically equating five overlapping levels of a mathematics computation test. One to four test levels were administered within intact classrooms to randomly equivalent groups of third through eighth grade students. Test characteristic curves were derived for each grade/test level combination. It was generally found that an examinee would receive a higher ability estimate if the test level administered had been calibrated on less able examinees. Practical implications for "out-of-level" and adaptive testing are discussed.
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    Effect of examinee group on equating relationships
    (1986) Harris, Deborah J.; Kolen, Michael J.
    Many educational tests make use of multiple test forms, which are then horizontally equated to establish interchangeability among forms. To have confidence in this interchangeability, the equating relationships should be robust to the particular group of examinees on which the equating is conducted. This study investigated the effects of ability of the examinee group used to establish the equating relationship on linear, equipercentile, and three-parameter logistic IRT estimated true score equating methods. The results show all of the methods to be reasonably independent of examinee group, and suggest that population independence is not a good reason for selecting one method over another.
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    Effects of passage and item scrambling on equating relationships
    (1991) Harris, Deborah J.
    This study investigated the effects of passage and item scrambling on equipercentile and item response theory equating using a random groups design. For all four tests and for both scramblings used, differences in item and examinee statistics were found to exist between all three forms used (the base form and the two scrambled forms). Up to 50% of the examinees administered a scrambled form would have received a different scale score if the base form equating, rather than the scrambled form equating, had been used to convert their number-correct scores. It is, therefore, suggested that caution be used when scrambled forms are being administered, because in applications such as that studied here, the effects of applying the equating results obtained using a base form to the number-correct scores obtained on a scrambled form can be quite substantial in terms of the numbers of examinees who would receive different scores. Index terms: context effects, equating, item scrambling.