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Some Paths Toward Making PRAXIS Scores More Useful

Wainer, Howard; Sheehan, Kathleen M.; Wang, Xiaohui
Publication Year:
Report Number:
ETS Research Report
Document Type:
Page Count:
Subject/Key Words:
Bayesian Statistics, Reliability, Subscores, Scoring Formulas, Praxis


This study describes an analytic method for aiding in the generation of subscales that characterize the deep structure of tests. In addition, a procedure was derived for estimating scores for these scales that are more statistically stable than subscores computed solely from the items contained on that scale. Score stability is achieved through augmentation with other related information on the test. These methods were used to complement each other on a data set obtained from a PRAXIS administration. The deep structure of the test was found to yield 10 subscales. Students' performance on the test was, however, essentially unidimensional, and hence the 10 subscores could be computed with very high reliability. This result was contrasted with the calculation of 6 traditional subscales based on surface features of the items. These subscales could also provide augmented subscores of high reliability.

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