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ERIC Number: ED429092
Record Type: Non-Journal
Publication Date: 1999-Jan
Pages: 62
Abstractor: N/A
Accuracy of Course Placement Validity Statistics under Various Soft Truncation Conditions. ACT Research Report Series 99-2.
Schiel, Jeff L.; King, Jason E.
Analyses of data from operational course placement systems are subject to the effects of truncation; students with low placement test scores may enroll in a remedial course, rather than a standard-level course, and therefore will not have outcome data from the standard course. In "soft" truncation, some (but not all) students who score below the cutoff for a standard course enroll in and complete the course. Previous research, using one particular definition of soft truncation, showed that reasonably accurate validity statistics can be estimated under this condition. Alternative definitions of soft truncation could conceivably result in different validity statistics. This simulation study therefore examined an alternative definition of soft truncation, in which students who score just below the cutoff have a higher probability of enrolling in the standard course than do relatively lower scoring students. The effects of different combinations of soft truncation condition, logistic regression curve, test score distribution shape, and sample size on estimated optimal cutoff scores, accuracy rates, and success rates were summaries. Postsecondary institutions that experience a moderate degree of soft truncation (e.g., 20% to 60% of their respective placement groups) can expect to obtain acceptably accurate estimates of optimal cutoff scores, irrespective of the steepness of the logistic curve and the skewness of the marginal distribution of the predictor variable. An appendix contains figures illustrating the effects of soft truncation on estimated success rate by placement group. (Contains 27 figures, 5 tables, and 7 references.) (Author)
ACT Research Report Series, P.O. Box 168, Iowa City, IA 52243-0168.
Publication Type: Reports - Evaluative
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: American Coll. Testing Program, Iowa City, IA.