The relationship between chi-square statistics from matched and unmatched analyses.

The McNemar chi-square statistic for testing the equality of proportions in matched pairs of binary data is expressed as a function of the Pearson chi-square statistic and a kappa statistic for measuring interrater agreement. Implications for data analysis and for sample size determination are discussed. The result is generalized to provide a similar relationship between Cochran's Q-statistic and the Pearson chi-square statistic for the comparison of proportions in matches of size m.