Compare proportion with a dichotomous outcome between two samples, using the Chi-squared statistic (or z test).

Instructions: Enter parameters in the red cells. Answer will appear in the blue cells.

Enter any ONE of the following three parameters (the other two will be calculated automatically):

The standard normal deviate for α = Z_{α} = 0.000

The standard normal deviate for β = Z_{β} = 0.000

Pooled proportion = P = (q_{1}*P_{1}) + (q_{0}*P_{0}) = 0.000

A = Z_{α}√P(1-P)(1/q_{1} + 1/q_{0}) = 0.000

B = Z_{β}√P_{1}(1-P_{1})(1/q_{1}) + P_{0}(1-P_{0})(1/q_{0}) = 0.000

C = (P_{1}-P_{0})^{2} = 0.000

Total group size = N = (A+B)^{2}/C = 0

Continuity correction (added to N for Group 0) = CC = 1/(q_{1} * |P_{1}-P_{0}|) = 0

Note:

This calculator uses the normal distribution (with and without the continuity correction) as an approximation to the binomial distribution.

References:

Hulley SB, Cummings SR, Browner WS, Grady D, Newman TB. Designing clinical research : an epidemiologic approach. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2013. Appendix 6B, page 75.

(Continuity Correction) Fleiss JL, Tytun A, Ury HK. A simple approximation for calculating sample sizes for comparing independent proportions. Biometrics 1980;36:343-46.