In
statistics and
epidemiology,
relative risk or
risk ratio (
RR) is the ratio of the
probability of an event occurring (for example, developing a disease, being injured) in an exposed group to the probability of the event occurring in a comparison, non-exposed group. Relative risk includes two important features: (i) a comparison of risk between two "exposures" puts risks in context, and (ii) "exposure" is ensured by having proper
denominators for each group representing the exposure