SELECTION OF ONE-STAGE SAMPLE SIZE IN CHEN-CHEN-CHANG’S ˜R TEST AND AN EVALUATION OF THE PERFORMANCE OF ˜R

In this study, in order to determine the one-stage sample size, power comparisons were made in the ˜R test suggested by Chen et al. for ordered alternatives, and the Jonckheere-Terpstra J test, which is one of the classic test statistics, was compared with ˜R in terms of effectiveness. The simulation concerning power comparisons showed that it is impossible to randomly select the one-stage sample size represented by n0 in ˜R , based on one-stage sampling, and that the one-stage sample size should be as large as possible. In addition, the recently-suggested ˜R test statistic for ordered alternatives was compared with J in terms of experimental type-I error and power. Whilst ˜R and J yielded almost the same results in terms of experimental type-I error, ˜R was found to give a worse performance than J with regard to power. The results obtained were validated for different sample sizes and different numbers of populations.