The capture-recapture method serves to estimate a quantity (e.g. people with a specific trait) from a population.In epidemiology it is most commonly used to conduct measurements in a population that you cannot count completely.
The technique derives from counting animals, where a certain amount of animals where captured and marked and then released again. After a certain period of time a second sample of the animals were taken. The amount of marked animals in this second sample allows to draw conclusions about the true size of the population. (https://wiki.ecdc.europa.eu/fem/w/wiki/1218)
