Trends in Mortality among British Doctors in Relation to Their Smoking Habits

On 31 October 1951, Doll and Hill sent a questionary to all members of the medical profession in the United Kingdom enquiring about their smoking habits. On the basis of their replies 40,637 doctors (34,445 men and 6,192 women) could then be classified in a few broad groups according to their age, the amount of tobacco they smoked, their method of smoking, and whether smoking had been continued or abandoned. Further questionaries were sent