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Approximate sample size formulas for the two‐sample trimmed mean test with unequal variances
Author(s) -
Luh WeiMing,
Guo JiinHuarng
Publication year - 2007
Publication title -
british journal of mathematical and statistical psychology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.157
H-Index - 51
eISSN - 2044-8317
pISSN - 0007-1102
DOI - 10.1348/000711006x100491
Subject(s) - mathematics , sample size determination , statistics , truncated mean , statistic , sample (material) , normality , f test of equality of variances , test statistic , sample mean and sample covariance , statistical hypothesis testing , power (physics) , chemistry , physics , chromatography , quantum mechanics , estimator
Yuen's two‐sample trimmed mean test statistic is one of the most robust methods to apply when variances are heterogeneous. The present study develops formulas for the sample size required for the test. The formulas are applicable for the cases of unequal variances, non‐normality and unequal sample sizes. Given the specified α and the power (1−β), the minimum sample size needed by the proposed formulas under various conditions is less than is given by the conventional formulas. Moreover, given a specified size of sample calculated by the proposed formulas, simulation results show that Yuen's test can achieve statistical power which is generally superior to that of the approximate t test. A numerical example is provided.