Free statistical calculators
Comparison of proportions calculator
MedCalc uses the "N-1" Chi-squared test as recommended by Campbell (2007) and Richardson (2011).
The confidence interval is calculated according to the recommended method given by Altman et al. (2000).
- Altman DG, Machin D, Bryant TN, Gardner MJ (Eds) (2000) Statistics with confidence, 2nd ed. BMJ Books. (p. 49)
- Campbell I (2007) Chi-squared and Fisher-Irwin tests of two-by-two tables with small sample recommendations. Statistics in Medicine 26:3661-3675.
- Richardson JTE (2011) The analysis of 2 x 2 contingency tables - Yet again. Statistics in Medicine 30:890.