Excess risk

In statistics, excess risk is a measure of the association between a specified risk factor and a specified outcome (such as contracting a disease). It is the difference between two proportions—in epidemiology it's typically defined to be the difference between the proportion of subjects in a population with a particular disease who were exposed to a specified risk factor and the proportion of subjects with that same disease who were not exposed. That is,

$ER = P(D \mid E) - P(D \mid \bar{E})$

where $\bar{E}$ denotes the event "not E."

Note that this definition entails that -1 ≤ ER ≤ 1.

External links

• Excess risk