Relative risk divides the incidence rate among exposed persons by the rate among unexposed persons. A value of one indicates no association, above one indicates elevated risk, and below one indicates a protective effect.
It is calculated from cohort studies.
Alternative Names:
Risk Ratio, RR
Why it Matters?
The relative risk of two argument holds that a value above two means exposure more likely than not caused an individual case, since more than half of cases in the exposed group are attributable to exposure. Courts have divided on whether that threshold is required for specific causation, with some treating it as necessary and others as one consideration. The argument is a recurring feature of pharmaceutical and toxic tort Daubert practice.
Frequently Confused with
Related terms
Frequently asked questions
What does relative risk above two mean?
Is that threshold required?
