What is relative risk?

Relative risk (RR) is a statistical measure used to compare the risk of a certain event occurring in two different groups. It is calculated by dividing the incidence rate of the event in the exposed group by the incidence rate in the unexposed group. An RR greater than 1 indicates a higher risk in the exposed group, while an RR less than 1 suggests a lower risk. It is commonly used in epidemiological studies to evaluate the strength of an association between exposure and outcomes, such as diseases.