Relative Risk

Relative risk is an epidemiological measure expressing how much more likely an exposed population is to develop a specific injury or disease compared to an unexposed control group, calculated as the ratio of incidence rates between the two groups. In mass tort litigation, plaintiffs' experts rely on relative risk figures derived from epidemiological studies to help establish general causation — that a drug, device, or toxic substance is capable of causing the alleged harm. A relative risk greater than 2.0 is frequently cited in toxic tort contexts as a threshold relevant to whether the exposed group's risk is more than doubled, which bears on causation arguments, though courts evaluate this evidence under applicable expert admissibility standards. Plaintiff firms and their media intelligence teams monitor published epidemiological literature for relative risk data when evaluating whether a new tort has sufficient scientific support to justify a funded advertising campaign.