Spearman’s Rho: Formula, Worked Example and Table
Spearman's rho was invented by a psychologist, yet the rank formula Charles Spearman printed in 1904 is not the one students learn today. His version …
Tag: non-parametric tests
Wilcoxon Signed-Rank Test: Formula, Worked Example and Table
In 1945 the chemist Frank Wilcoxon introduced the Wilcoxon signed-rank test in a four-page paper and tried it on Darwin's maize plants. It reached the…
Mann-Whitney U Test: Formula, Worked Example and Table
The Mann-Whitney U test is often described as a test of medians, but it is not one. Two groups with identical medians can still produce a significant …
Which Statistical Test to Use in Psychology: A Decision Guide
In a review of 513 neuroscience papers, of the studies where a particular comparison mattered, 79 used the wrong statistical procedure and only 78 use…
The Sign Test: Formula, Worked Example and Critical Values
In 1710, a royal physician counted London christening records for 82 straight years, found boys outnumbered girls every single year, and published wha…