Date last tested: 9/27/05.

Comparison of ‘Two-sample Independent t-test’ to other public software programs and statistical textbook.

Two-tailed p-value

| CI %, n1, mean1, s1 n2, mean2, s2
Data input | 95%, 7, 11.57142857, 8.81016729, 18, 7.44444444, 3.69772939 | 95%, 64, 54.4375, 12.05657958, 35, 47.42857143, 13.15582115 | 95%, 78, 92.88461538, 15.34451192, 46, 88.02173913, 12.20653583
OpenEpi Equal variance Unequal variance | 0.1062 0.2705 | 0.0087 0.0113 | 0.0692 0.0544
SAS Equal variance Unequal variance | 0.1062 0.2705 | 0.0087 0.0113 | 0.0692 0.0544
GraphPad Software Equal variance Unequal variance | 0.1062 0.2705 | 0.0087 0.0113 | 0.0692 0.0544

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

Reference:

· Bernard Rosner. Fundamentals of Biostatistics (5th edition).

· SAS Institute (Statistical Analysis System-version 8, Cary, North Carolina, USA)

· GraphPad Software. QuickCalc online calculators for scientists. (http://graphpad.com/quickcalcs/ttest1.cfm?Format=SD)