A matched pairs t test is employed when the data consists of pairs of observations that are inherently linked. Common scenarios include:
Pre- and post-intervention measurements on the same subjects. Comparing outcomes between matched cases and controls. Before-and-after studies in public health interventions.
For instance, if you are investigating the effect of a new vaccine on a population, you might measure the incidence of a disease before and after the administration of the vaccine in the same individuals.
