Wilcoxon W: what it means and how to read it
In the report: Wilcoxon W — The rank sum of the group whose U is the smaller one — Wilcoxon's rank-sum form of the same test, as SPSS.
How to read it
The same test as U written another way; U is the one usually reported.
In plain words
A teacher compared two groups of students, and the report showed two numbers, U = 12 and W = 67. She could not tell which one to write down. W is the same test written another way. All students are lined up from the lowest score to the highest, and W puts together the place numbers of the group that stood lower. Both numbers tell the same story: this group stood low in the line. Now she knows she can report U, which most people use, and skip W without losing anything.
Example
The cell with Wilcoxon W is selected in each report; point at a label to see its note.
- — the sample data (50 rows) the examples use
- — two-sided
=STATS_MANN_WHITNEY(Data!A1:T51, "before,after")
Where you see it
STATS_MANN_WHITNEY— Mann–Whitney U test for two independent samples — the rank replacement for STATS_INDEPENDENT when the data are not normal (see STATS_NORMALITY), are ranks or rating scales (1–5), or have outliers.
Related values
- Kruskal–Wallis H — How far the mean ranks of the groups are apart, with the tie correction.
- Statistic — The test statistic.
- Pearson chi-square — Pearson's chi-square: how far the observed counts are from those expected if the two variables were unrelated. No continuity correction.
- Pearson Chi-Square — The same test as the chi2 at the top of the report, in the SPSS table: value, df and the asymptotic p from the chi-square distribution. No continuity correction.
- Continuity Correction (Yates) — Pearson's chi-square with the Yates correction, for a 2 × 2 table only; the row is absent for larger tables.
Get it in your sheet
One formula in a cell gives the whole report, Wilcoxon W included. ALS Stats is a free add-on for Google Sheets™.
Install ALS Stats from Google Workspace Marketplace (opens in a new tab)