Table PTT1U. Two group continuity corrected Chi-square test of equal proportions (unequal n’s)

Computed using the large sample normal approximation shown in the nQuery Advisor® manual appendix modified for unequal n’s; see Fleiss JL, Tytun A, Ury SHK (1980) A simple approximation for calculating sample sizes for comparing independent proportions, Biometrics 36:343-346 for details. Figure PTT1U shows computations for one example from Fleiss JL (1981) Statistical Methods for Rates and Proportions, 2nd edition, John Wiley & Sons, Inc. New York. Solutions for range of parameter values used for PTT0U checked against answers from PTT1 and PTT0U.

Figure PTT1U. In the first three columns, nQuery Advisor® 7.0 has solved for sample size, in the fourth column, nQuery Advisor® 7.0 solved for power given r and n1.