Smoking and dementia in male British doctors: prospective study

A formula was incomplete in this paper by Richard Doll and colleagues (22 April, pp 1097-102). In the last sentence of the statistical methods section the formula for the 95% confidence limit of the relative risk should have been given as: “exp (b ± SE×1.96) [not exp(b SE 1.96)], where b is the log relative risk and SE its standard error.”