Document Detail


Sample size determinations for Welch's test in one-way heteroscedastic ANOVA.
MedLine Citation:
PMID:  23316952     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
For one-way fixed effects ANOVA, it is well known that the conventional F test of the equality of means is not robust to unequal variances, and numerous methods have been proposed for dealing with heteroscedasticity. On the basis of extensive empirical evidence of Type I error control and power performance, Welch's procedure is frequently recommended as the major alternative to the ANOVA F test under variance heterogeneity. To enhance its practical usefulness, this paper considers an important aspect of Welch's method in determining the sample size necessary to achieve a given power. Simulation studies are conducted to compare two approximate power functions of Welch's test for their accuracy in sample size calculations over a wide variety of model configurations with heteroscedastic structures. The numerical investigations show that Levy's (1978a) approach is clearly more accurate than the formula of Luh and Guo (2011) for the range of model specifications considered here. Accordingly, computer programs are provided to implement the technique recommended by Levy for power calculation and sample size determination within the context of the one-way heteroscedastic ANOVA model.
Authors:
Show-Li Jan; Gwowen Shieh
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-14
Journal Detail:
Title:  The British journal of mathematical and statistical psychology     Volume:  -     ISSN:  2044-8317     ISO Abbreviation:  Br J Math Stat Psychol     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-15     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0004047     Medline TA:  Br J Math Stat Psychol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
© 2013 The British Psychological Society.
Affiliation:
Chung Yuan Christian University, Taiwan, Republic of China.
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