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)