Three methods of test equating (linear, equipercentile, and item response theory) were investigated with respect to the issue of scale drift. Results indicate that all three models work well in limited settings but that the item response theory approach provided the most stable results overall. (JKS)

The nonparametric approach to test theory discussed here has its roots in the early work of Guttman, Lazarsfeld, and Meredith; and more recently in the work of Cliff and in Tatsuoka and Tatsuoka. Mokken's extensive treatment of this subject concentrated on defining, constructing, and testing unidimensional scales, based on responses to dichotomous…

In this paper the bootstrap technique was applied to the evaluation of potential predictive bias for different ethnic groups using the Scholastic Aptitude Test (SAT) and high school ranks to predict college grade point averages (GPAs). Data of three ethnic groups were used; the total number of subjects was close to 5,000. Both conventional…

This statistical study attempted to determine the average age, mental rating, geographic distribution, present and prior commitments, and races of the initial group of 39 Newgate students at the Federal Youth Center, Ashland, Kentucky. The results indicated that (1) the average age was 18 plus; (2) the highest grade completed upon entering the…

Three item response models were evaluated for estimating item parameters and equating test scores. The models, which approximated the traditional three-parameter model, included: (1) the Rasch one-parameter model, operationalized in the BICAL computer program; (2) an approximate three-parameter logistic model based on coarse group data divided…

A previous study of pre-equating the Scholastic Aptitude Test (SAT) using item response theory provided unacceptable equating results for SAT-mathematical data. The purpose of this study was to investigate two possible explanations for these unacceptable pre-equating results. Specifically, the calibration process, which made use of the…

This study tests several explanations for discrepant results in an earlier study (Cook et al., 1985) which presented a partial pre-calibration method for equating new editions of the Scholastic Aptitude Test (SAT) to the same scale as older editions. In contrast to full pre-calibration, which seeks to equate all items from two or more editions,…