ABSTRACT
The Wilcoxon matched-pairs test determines the significance of the difference between two sets of ranks obtained from matched pairs. Because rank order is important to the test, it is also called the Wilcoxon signed-rank test. The Wilcoxon matched-pairs test can also be used with interval or ratio data, so it can do more than just compare rank ordering pre and post. The Wilcoxon matched pairs test is equivalent to the t-test for dependent groups, except for one difference. The Wilcoxon matched pairs test does not assume that the data are normally distributed. The statistical name for non-normal situations is nonparametric. This chapter investigates neural correlates of infants' detection of pro- and antisocial agents. The excerpt reports on infant perception of pro and antisocial agents. The researchers used a Wilcoxon matched pairs approach because the P400 data was non-normal. The study is matched pairs, because the researchers compared P400 activity within each infant.
