2 × 2 Tables: a note on Campbell's recommendation

Abstract

For 2 × 2 tables, Egon Pearson's N - 1 chi-squared statistic is theoretically more sound than Karl Pearson's chi-squared statistic, and provides more accurate p values. Moreover, Egon Pearson's N - 1 chi-squared statistic is equal to the Mantel-Haenszel chi-squared statistic for a single 2 × 2 table, and as such, is often available in statistical software packages like SPSS, SAS, Stata, or R, which facilitates compliance with Ian Campbell's recommendations.

Keywords: Mantel-Haenszel chi-squared statistic; N − 1 chi-squared statistic; Pearson's chi-squared statistics; R; SAS; SPSS; Stata; r; statistical software; χ2; ϕ.