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)