Relative and absolute risk, explained

Stating risks in absolute rather than relative terms should be standard practice for science writers because it puts the numbers in clear perspective, Joy Victory writes: "Knowing only the relative data is like having a 50% off coupon for selected items at a department store. But you don’t know if the coupon applies to a diamond necklace or to a pack of chewing gum. Only by knowing what the coupon’s true value is — the absolute data — does the 50% have any meaning."