Fundamentals of Statistics contains material of various lectures and courses of H. Lohninger on statistics, data analysis and chemometrics......click here for more. 
Home Statistical Tests Means and Medians TwoSample tTest TwoSample tTest  
See also: survey on statistical tests, comparing means, distribution calculator, ANOVA  
TwoSample tTestSo far we have tested sample means to ascertain how well they agree with μ of the underlying population. However, we often want to compare the mean of different populations, e.g. compare products of two different companies, or one medical therapy vs. another, etc. In effect, we use the same procedures as when inferring from a population. Modifications have to be made to accommodate the fact that we are comparing two estimated values and not an estimated with a true value. 

Home Statistical Tests Means and Medians TwoSample tTest TwoSample tTest 