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: critical values
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 …
Chi-Squared Test in Psychology: Formula, Example, Table
For the first twenty-two years of its life, the chi-squared test used the wrong degrees of freedom. Karl Pearson gave a 2x2 table 3 instead of 1, unti…
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…