ABSTRACT
A prospective experiment is one that is conducted forwards in time. In a prospective cohort study, subjects are classified into groups depending on whether or not they are exposed to a risk factor. These groups of subjects, called ‘cohorts’ (Roman term meaning a tenth of a legion), are then followed over a time period after which exposed and non-exposed subjects are compared with regard to rates of development of an outcome of interest (Figure 5.1). This comparison between exposed and nonexposed groups is in order to identify any possible relationships that may exist between a risk factor and an outcome.
