Coefficient of Concordance

Proposed by Maurice G. Kendall and Bernard Babington Smith, Kendall's coefficient of concordance (W) is a measure of the agreement among several (m) quantitative or semiquantitative variables that are assessing a set of n objects of interest. In the social sciences, the variables are often people, called judges, assessing different subjects or situations. In community ecology, they may be species whose abundances are used to assess habitat quality at study sites. In taxonomy, they may be characteristics measured over different species, biological populations, or individuals.

There is a close relationship between Milton Friedman's two-way analysis of variance without replication by ranks and Kendall's coefficient of concordance. They address hypotheses concerning the same data table, and they use the same χ2 statistic for testing. They differ only ...