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ERIC Number: ED507808
Record Type: Non-Journal
Publication Date: 2009-Oct
Pages: 45
Abstractor: As Provided
Reference Count: 44
ISBN: N/A
ISSN: N/A
Strategies for Testing Slope Differences. Research Report. ETS RR-09-32
Moses, Tim; Klockars, Alan
Educational Testing Service
The robustness and power of 9 strategies for testing the differences in groups' regression slopes were assessed under nonnormality and residual variance heterogeneity. For the conditions considered, the most robust strategies were the trimmed and Winsorized slope estimates used with the James second-order test, the Theil-Sen slope estimates used with James, and the Theil-Sen estimates used with percentile bootstrapping. The use of Theil-Sen slope estimates produced more powerful tests than the use of trimmed and Winsorized slopes. Appendices include: (1) The Minimum Maximum Likelihood Type (MM) Regression Algorithm; and (2) The Critical Value of the James Second-Order Test Statistics. (Contains 11 tables and 4 figures.)
Educational Testing Service. Rosedale Road Mailstop 19R, Princeton, NJ 08541-0001. Tel: 609-921-9000; Fax: 609-734-5410; Web site: http://www.ets.org
Publication Type: Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: Educational Testing Service