Nonparametric step-down test procedures for finding minimum effective dose

Nonparametric versions of normal theory step-down multiple-test procedures for inferring minimum effective dose (see Tamhane et al. Citation[1]) were developed and studied by Monte Carlo simulation. Two types of step-down testing procedures were examined. For both procedures, pair wise, linear, or Helmert contrasts of mean ranks were studied. All nonparametric step-down procedures controlled familywise error rate under normal, double exponential, and exponential distributions. Specific recommendations based on power and bias comparisons of nonparametric methods among themselves, with Shirley's Citation[2]test, and with parametric step-down multiple-test procedures are given.