Wilcoxon W. This is NOT an estimate of the difference in medians. The Wilcoxon test is a nonparametric test designed to evaluate the difference between two treatments or conditions where the samples are correlated.
The SMALLER it is taking into account how many participants you have then the less likely it is to have occurred by chance. The Wilcoxon test statistic W. Its particularly recommended in a situation where the data are not normally distributed.
If the null hypothesis is true we expect to see similar numbers of lower and higher ranks that are both positive and negative ie W and W- would be similar.
The Wilcoxon test statistic W. U critical which is reported in the table below for different combinations of sample-sizes N 1 and N 2 and false-positive rates α then we would reject the null hypothesis H o of no group differences bwtween the two samples. 6The sampling distribution of the Wilcoxon rank sum statistic under the various choices for. The W statistic is a non-parametric test thus it does not need multivariate normality in the data.
