relative risk A data item that equals the incidence in exposed individuals divided by the incidence in unexposed individuals. The relative risk can be calculated from studies in which the proportion of patients exposed and unexposed to a risk is known, such as a cohort study. Yongqun He WEB: http://www.uptodate.com/contents/glossary-of-common-biostatistical-and-epidemiological-terms derived data from inferential statistical analysis