Attributable risk measures the excess incidence in the exposed population over the background rate. The attributable fraction expresses that excess as a proportion of total cases among the exposed.
It is derived from relative risk.
Alternative Names:
Attributable Fraction, Excess Risk
Why it Matters?
The attributable fraction is the quantity underlying the more-likely-than-not argument, since a fraction above fifty percent means most cases among exposed persons resulted from exposure. That corresponds to a relative risk above two. Framing the causation argument in attributable fraction terms is sometimes clearer for a factfinder than relative risk, because it directly answers what portion of cases the exposure explains.
Frequently Confused with
Related terms
Frequently asked questions
How does attributable fraction relate to relative risk?
Why frame causation this way?
