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ERIC Number: EJ1051930
Record Type: Journal
Publication Date: 2015
Pages: 28
Abstractor: As Provided
ISSN: ISSN-0022-0973
Reexamining the Impact of Nonnormality in Two-Group Comparison Procedures
Kang, Yoonjeong; Harring, Jeffrey R.; Li, Ming
Journal of Experimental Education, v83 n2 p147-174 2015
The authors performed a Monte Carlo simulation to empirically investigate the robustness and power of 4 methods in testing mean differences for 2 independent groups under conditions in which 2 populations may not demonstrate the same pattern of nonnormality. The approaches considered were the t test, Wilcoxon rank-sum test, Welch-James test with trimmed means and Winsorized variances, and a nonparametric bootstrap test. Results showed that the Wilcoxon rank-sum test and Welch-James test with trimmed means and Winsorized variances were not robust in terms of type I error control when the 2 populations showed different patterns of nonnormality. The nonparametric bootstrap test provided power advantages over the t test. The authors discuss other results from the simulation study and provide recommendations.
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A