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Can tests for treatment group equality be improved?: The bootstrap and trimmed means conjecture
Author(s) -
Wilcox Rand R.,
Keselman H. J.,
Kowalchuk Rhonda K.
Publication year - 1998
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 - 10.1111/j.2044-8317.1998.tb00670.x
Subject(s) - conjecture , mathematics , statistics , group (periodic table) , truncated mean , econometrics , combinatorics , chemistry , organic chemistry , estimator
Westfall & Young's (1993) results suggest that by combining bootstrap methods with methods based on trimmed means researchers can obtain better Type I error control when testing for treatment group equality. Thus, the methods due to Alexander & Govern (1994), Box (1954), and Welch (1951) were compared under conditions of non‐normality and variance heterogeneity when group sizes were unequal, conditions known to produce liberal rates of error. We found that, typically, in one‐way designs better Type I error control can indeed be obtained when the bootstrap method is used in conjunction with test statistics based on trimmed means.