Nonparametric tests for identification of the minimum effective dose and applications

Information on the activity of a substance is often obtained from experiments in which the treatments comprise several dose levels of the substance and a zero dose control. The aim of such experiments, particularly in toxicological and drug development studies are determine the lowest dose, if any, at which there is activity. Another way of explaining the aim is determining the minimum effective dose (MED) in a dose- response study, where the MED is defined to be the lowest dose level producing an effect over that of the zero dose control. Introduction of this study, after informed the literature connected with subject in second part; Nonparametric test procedure proposed by Shirley, Nonparametric procedure based on the Mann-Whitney statistic incorporated with the step-down closed testing scheme, Wilcoxon type nonparametric equivalent of Williams? test and finally proposed by Williams test statistic introduced, in third part done application of these tests based on a real data. In fourth part, touched on to results and comments.