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: ordinal data
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 …
Levels of Measurement: Nominal, Ordinal and Interval
Levels of measurement decide which statistical test you are allowed to run, and AQA devotes 25 to 30 per cent of the entire Psychology assessment to r…