Wilcoxon Rank Score. The Wilcoxon test is a nonparametric test designed to evaluate the difference between two treatments or conditions where the samples are correlated. In the new drug group the sum of the ranks is 18.
As a check on our assignment of ranks we have n n12 8 92 36 which is equal to 324. May 04 2017 Specifically we produce a test statistic based on the ranks. Only with a high value for alpha and extremely lopsided data.
Whereas the dependent samples t-test tests whether the average difference between two observations is 0 the Wilcoxon test tests whether the difference between two observations has a mean signed rank of 0.
In particular it is suitable for evaluating the data from a repeated-measures design in a situation where the prerequisites for a dependent samples t-test are not met. Compute the test statistic Wilcoxon W which is the sum over positive signed ranks. That is to say difference scores above zero represent caffeine performance exceeds placebo. The smallest has rank 1 the 2nd smallest rank 2 and so on.
