Table: Report one-way Kruskal-Wallis...

Performs a one-way Kruskal-Wallis analysis on the data in one column of a selected Table and reports the results in the info window. This test is sometimes refered to as a one-way analysis of variance for non-normally distributed data.

Settings

Column with data
the label of the column who's data will be analyzed.
Factor
the label of the column with the names of the levels.

Algorithm

The analysis is done on the ranked data and consists of the following steps:

1. Rank all the N data points together, i.e. rank the data from 1 to N.
2. The test statistic is:
K = (12 / (N(N+1)) Σi=1g ni (meanRanki)2 - 3(N+1),
where g is the number of levels, ni the number of data in i-th level and meanRanki the average rank of the i-th level.
3. The p value is approximated by the χ2 (K, g - 1) distribution.

© djmw, June 17, 2012