Comparison of OpenEpi module ‘Sample Size For Comparing Two Means’ to other public software and statistical textbook.

Date last tested: 7/11/05.

| CI %, power %, ratio of n2 /n1, Mean difference (Group 1 – Group 2), s1, s2.
Data input | 95%, 80%, 1, 5.42, 15.34, 18.23 | 95%, 80%, 2, 5.42, 15.34, 18.23 | 95%, 80%, 1, -0.24, 0.64, 0.76 | 95%, 90%, 2, 1, 3.0, 2.8
OpenEpi | n1 = 152 n2 = 152 | n1 = 108 n2 = 216 | n1 = 135 n2 = 135 | n1 = 133 n2 = 133
Rosner | n1 = 152 n2 = 152 | n1 = 108 n2 = 216 | n1 = 135 n2 = 135 | n1 = 133 n2 = 133

‘CI’ Confidence interval; ‘n1’ sample size of Group 1; ‘n2’ sample size of Group 2; ‘s1’ standard deviation of Group 1 ‘s2’ standard deviation of Group 2;

Reference:

· Bernard Rosner. Fundamentals of Biostatistics (5th edition). (data obtained from examples and problems)