Absolute and Relative Risk
Relative risk is the proportional change; absolute risk is what it means for you in real numbers.
What it means
Two ways of describing the same change, one of which sounds dramatic and one of which is useful.
Relative risk — the proportional change. "Doubles your risk." "Reduces risk by 50%."
Absolute risk — what actually happens to real numbers of people. "From 1 in 10,000 to 2 in 10,000."
Both of those describe exactly the same thing. One reads as alarming, the other as trivial — and the second is the honest one.
This is the single most common way health statistics mislead, in newspapers and in medicine alike. A relative figure without an absolute one is close to meaningless.
In practice
In every health headline you have ever read, almost always as relative risk, because it is the bigger number.
Also in medication discussions — a statin "reducing heart attack risk by a third" means something quite different for someone with 3% risk than for someone with 30%.
Why it matters
Always ask: from what to what? That one question converts a relative figure into something you can actually reason about.
Ask what it means for someone like you, since baseline risk varies enormously with age and health.
Be suspicious of any percentage with no baseline attached. It is not necessarily dishonest, but it is incomplete.
Clinically reviewed by Dr Mohammad Zubair Khan, GMC 7563469
Last reviewed
August 30, 2026