Find over 25,000 psychological definitions


Wilcoxon rank-sum test

a statistical test of centrality for ranked data that compares the median values of two independent samples to determine whether they have been drawn from the same population. In this nonparametric equivalent of the t test, one combines the data points from the different groups into a single pool and ranks their values in ascending order. The ranks that have been assigned are, in turn, used to determine the test statistic, W, which is evaluated for statistical significance. The calculations involved in the Wilcoxon rank-sum test are nearly identical to those for the Mann–Whitney U test. [Frank Wilcoxon]

Browse dictionary by letter

a b c d e f g h i j k l m n o p q r s t u v w x y z

Psychology term of the day

April 17th 2024

axial gradient

axial gradient

the difference in development or metabolic rate of tissues along a body axis. See also anterior–posterior development gradient.