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The Validity of Law School Admission Test Scores for Repeaters: A Replication (TR-98-05)
Susan P. Dalessandro and Lori D. McLeod

Executive Summary

The fair and accurate treatment of multiple-test scores for law school applicants who take the Law School Admission Test (LSAT) more than one time is the focus of this study. The conclusion from earlier research studies is that the simple arithmetic average of multiple scores provides the best prediction of subsequent law school performance for repeaters. Since the content and scoring of the LSAT have changed since the Wightman 1990 study, the current study reexamines the differential validity and predictive accuracy of the different test scores that are presented by repeat test takers. In particular, the study examines the validity of using the (1) most recent, (2) initial, (3) highest, and (4) average score for repeaters.

The study includes U.S. law schools that participated in the Law School Admission Council (LSAC) Correlation Studies in 1996 and 1997. Data for four entering classes, from the fall of 1993 through the fall of 1996, were combined within each school. The sample contains only the 152 schools whose combined four-year enrollment included a total of 50 or more first-year students who had taken the LSAT on more than one occasion. Data were combined across four years in order to obtain sample sizes large enough to assure stability in the validity estimates. In addition to validity data, the study also provides descriptive data comparing one-time test takers with repeat test takers. Repeat test takers tend to earn lower LSAT scores than one-time test takers regardless of whether initial, most recent, highest, or average score is considered. One-timers also tend to have slightly higher undergraduate and first-year law school grade-point averages.

A primary concern for LSAT score users with regard to repeat test takers is the question of which of the scores or score combinations obtained from repeat test takers will most accurately predict subsequent performance in law school. Despite the changes in the LSAT, the results of the replication study support the original recommendation to use the arithmetic average of multiple test scores. A primary advantage of the average score is that it makes use of all the data that are available about the applicant. Further, no other score has been found to be superior to it. The data in this and previous studies also underscore the need to consider individual circumstances when evaluating scores for repeat test takers. That is, although the aggregate statistics confirm that, overall, using the average score for repeaters provides more accurate prediction of first-year grades, there are individual test takers for whom this is not the case. As important, there are examples in which one of the other score options would provide more accurate information about an individual applicant. In some instances, the initial score provides the best prediction of first-year law school performance. Intervening preparation may result in higher scores that overpredict subsequent law school performance. In other instances, the initial score does not accurately reflect the ability of the test taker and the test taker self-selected to repeat the test in order to obtain a more accurate reflection of his or her ability.

If a general rule that will be most fair to the majority of law school applicants is to be applied, the data continue to support the recommendation of the average score for general use. Regardless, score users need to be sensitive to individual differences among test takers and evaluate multiple scores in the context of additional information.

The Validity of Law School Admission Test Scores for Repeaters: A Replication (TR-98-05)

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