Analysis of ordered covariate effects among groups with repeated measurements

Chul Gyu Park, Taesung Park, Dong Wan Shin

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Testing procedures for ordered covariate effects are developed in the repeated measures experiment. The maximum likelihood estimators of covariate effects under the ordered hypothesis are approximated by the isotonic regression of their unconstrained estimators. The asymptotic null distributions of the test statistics are chi-bar-square distributions which are mixtures of chi-square distributions. A Monte-Carlo simulation reveals that the proposed test for ordered covariate effects is seriously more powerful than the usual chi-square test that neglects the information on the order restriction. These testing methods are applied for analyzing the effect of vitamin E diet supplement on growth rate of animals.

Original languageEnglish
Pages (from-to)2291-2301
Number of pages11
JournalCommunications in Statistics - Theory and Methods
Issue number10
StatePublished - 1997


  • Chi-bar-square distribution
  • Isotonic regression
  • Likelihood ratio test
  • Ordered hypothesis


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