Relative risk

In epidemiology, risk ratio (RR) or relative risk is the ratio of the probability of an outcome in an exposed group to the probability of an outcome in an unexposed group. It is computed as I e / I u {displaystyle I_{e}/I_{u}} , where I e {displaystyle I_{e}} is the incidence in the exposed group, and I u {displaystyle I_{u}} is the incidence in the unexposed group. Together with risk difference and odds ratio, risk ratio measures the association between the exposure and the outcome. In epidemiology, risk ratio (RR) or relative risk is the ratio of the probability of an outcome in an exposed group to the probability of an outcome in an unexposed group. It is computed as I e / I u {displaystyle I_{e}/I_{u}} , where I e {displaystyle I_{e}} is the incidence in the exposed group, and I u {displaystyle I_{u}} is the incidence in the unexposed group. Together with risk difference and odds ratio, risk ratio measures the association between the exposure and the outcome. Risk ratio is used in the statistical analysis of the data of experimental, cohort and cross-sectional studies, to estimate the strength of the association between treatments or risk factors, and outcome. For example, it is used to compare the risk of an adverse outcome when receiving a medical treatment versus no treatment (or placebo), or when exposed to an environmental risk factor versus not exposed.