Two sample t-test

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:N(mu_i,sigma_i^2), where i=1,2

When carrying out a two sample t-test, it is usual to assume that the variances for the two populations are equal, i.e.sigma_1^2 = sigma_2^2 = sigma^2

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


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