Comparison of Asymptotically Distribution-Free Procedures for the Analysis of Complete Blocks

The Friedman test (or sign test when k = 2) depends entirely on within-block rankings. In a recent paper, Quade (1979) attempted to provide a test with more power than the Friedman test by considering a k-sample extension of the Wilcoxon signed ranks test. This is done by taking advantage of the between-block information. A third way to approach the problem and still retain both the within- and between-block information is first to transform all the observations to ranks from 1 to bk (b blocks and k treatments) and then to apply the parametric F test to the ranks. This approach is shown to be asymptotically distribution-free under suitable conditions. Computer simulation results indicate that this procedure is both robust and powerful for small sample sizes.