Robustness for Omnibus Tests using Trimmed Means under Violated Assumptions

  • Hyunchul Kim (Department of Education, Sungkyunkwan University, 3-53, Myungryun-Dong, Chongro-Ku, Seoul, Korea, 110-745)
  • Published : 1997.08.01


Univariate F test is based on the multisample sphericity assumption. Robustness for tests of a main effect of the within-subjects factor was investigated when the assumptions of the onmibus F tests are violated in a split-plot design with one between-subjects factor using untrimmed data and trimmed data. The results indicate that when sample sizes are unbalanced and dispersion matrices are heterogeneous, the CIGA and the $CIGA_T$ tests better control Type I error rates than do the $F_T$test and the$\widetilde{\xi_T}$test.



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