Comparison of several independent population means when their samples contain log-normal and possibly zero observations

Xiao Hua Zhou, Wanzhu Tu

Research output: Contribution to journalReview article

60 Scopus citations


In this paper, we consider the problem of testing the mean equality of several independent populations that contain log-normal and possibly zero observations. We first showed that the currently used methods in statistical practice, including the nonparametric Kruskal-Wallis test, the standard ANOVA F-test and its two modified versions, the Welch test and the Brown-Forsythe test, could have poor Type I error control. Then we propose a likelihood ratio test that is shown to have much better Type I error control than the existing methods. Finally, we analyze two real data sets that motivated our study using the proposed test.

Original languageEnglish (US)
Pages (from-to)645-651
Number of pages7
Issue number2
StatePublished - Jun 1 1999



  • Cost data
  • Log-normal
  • Maximum likelihood
  • Skewed distribution
  • Zero costs

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Public Health, Environmental and Occupational Health
  • Agricultural and Biological Sciences (miscellaneous)
  • Applied Mathematics
  • Statistics and Probability

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