Relative risk

Illustration of two groups: one exposed to treatment, and one unexposed. Exposed group has smaller risk of adverse outcome, with RR = 4/8 = 0.5.
The group exposed to treatment (left) has half the risk (RR = 4/8 = 0.5) of an adverse outcome (black) compared to the unexposed group (right).

The relative risk (RR) or risk ratio is the ratio of the probability of an outcome in an exposed group to the probability of an outcome in an unexposed group. Together with risk difference and odds ratio, relative risk measures the association between the exposure and the outcome.[1]

  1. ^ Sistrom CL, Garvan CW (January 2004). "Proportions, odds, and risk". Radiology. 230 (1): 12–9. doi:10.1148/radiol.2301031028. PMID 14695382.