Coefficient of Contingency

The coefficient of contingency is a Chi-square based measure of the relation between two categorical variables (proposed by Pearson, the originator of the Chi-square test).

Its advantage over the ordinary Chi-square is that it is more easily interpreted, since its range is always limited to 0 through 1 (where 0 means complete independence). The disadvantage of this statistic is that its specific upper limit is "limited" by the size of the table; C can reach the limit of 1 only if the number of categories is unlimited (for more information, see Siegel, 1956, p. 201).