Tuesday, November 18th, 2014
Good quote from Statistics Glossary:
A two sample t-test is a hypothesis test for answering questions about the mean where the data are collected from two random samples of independent observations, each from an underlying normal distribution:
When carrying out a two sample t-test, it is usual to assume that the variances for the two populations are equal, i.e.
The null hypothesis for the two sample t-test is:H0: µ1 = µ2
That is, the two samples have both been drawn from the same population. This null hypothesis is tested against one of the following alternative hypotheses, depending on the question posed.H1: µ1 is not equal to µ2
H1: µ1 > µ2
H1: µ1 < µ2