In comparing two population means of interval data, we must decide whether the samples are independent (in which case the parameter of interest is ) or matched pairs (in which case the parameter is ) in order to select the correct test statistic.

Independent Samples

Two or more groups of data that are collected from distinct, non-overlapping populations, allowing for comparisons that assume no inherent relationship between the groups.

Matched Pairs

A design in experiments where pairs of subjects are closely matched on key characteristics, with one subject in each pair receiving each treatment.

Test Statistic

A calculated value from sample data used to determine the p-value in hypothesis testing, assessing the likelihood of observing the results under the null hypothesis.