Glossary

Wilcoxon Rank Sums

Wilcoxon Rank Sums:

Wilcoxon rank sums are two statistic s T⁺ and T^– computed from paired replicates data .

Suppose we have two sets of pairs of measurements (x_i,y_i), i=1,…,N for each of N experimental units. We compute differences

d_i = y_i – x_i; i=1,…,N

and their absolute values:

D_i = |d_i|.

Then we replace D_i by ranks and split the values d_i into two groups according to the sign of corresponding d_i . The sums of ranks for positive and negative differences are named Wilcoxon rank sums T⁺ and T^– , respectively.

Wilcoxon rank sums are used to compute the test statistic for the Wilcoxon signed ranks test

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