The 2-Sample t conducts a hypothesis test of the difference between two population means when the population standard deviation, s is unknown. It also calculates a confidence interval of the mean. This procedure is based on the t-distribution which is derived from a normal distribution. The samples should be drawn independently from each other. For dependent samples, use the Paired t-test.
|Test||Null Hypothesis, H0||Alternate Hypothesis, H1|
|One-tailed||μ1 - μ2 = 0||μ1 - μ2 < d or μ1 - μ2 > d|
|Two-tailed||μ1 - μ2 = 0||μ1 - μ2 ≠ 0|
where μ1 and μ2 are the population means and d is the hypothesised difference between the population means.