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Note on the Equality of Variances in Two Sample t-Test
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 Title & Authors
Note on the Equality of Variances in Two Sample t-Test
Kim, Sang-Cheol; Lim, Jo-Han;
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 Abstract
Introductory statistic class proposes two tests for the equality of two population means according to the homogeneity of their variances. However, in practice, the variances are also unknown and practitioners often test their homogeneity before they do two sample t-test. This is also true in many popular statistical packages such as SAS and SPSS. In this paper, we study the type I error of this two stage procedure and propose a procedure to control it at a given significance level.
 Keywords
Homogeneity of variances;significance level;two sample t-test;
 Language
Korean
 Cited by
 References
1.
Gurland, J. and McCullouch, R. S. (1962). Testing equality of means after a preliminary test of equality of variances, Biometrika, 49, 403-416. crossref(new window)

2.
Moser, B. K. and Stevens, G. R. (1992). Homogeneity of variance in the two-sample means test, The American Statistician, 46, 19-21. crossref(new window)

3.
Moser, B. K., Stevens, G. R. and Watts, C. L. (1989). The two-sample T test versus satterthwaite's approximate F test, Communication in Statistics - Theory and Method, 18, 3963-3975. crossref(new window)