Editing British Doctors Study (section)

==Statistical analysis==
Response rates were quite high, making appropriate statistical analyses possible. The result was, that both lung cancer and "coronary thrombosis" (the then-prevalent term for [[myocardial infarction]], now commonly referred to as "heart attack") occurred markedly more often in smokers.

In the follow-up reports, published every ten years, more information became available. A major conclusion of the study is, for example, that smoking decreases life span up to 10 years, and that more than 50% of all smokers die of a disease known to be smoking-related, although the excess mortality depends on amount of smoking, specifically, on average, those who smoke until age 30 have no excess mortality, those who smoke until age 40 lose 1 year, those who smoke until 50 lose 4 years, and those who smoke until age 60 lose 7 years.<ref name="Doll2004">{{cite journal|vauthors=Doll R, Peto R, Boreham J, Sutherland I |title=Mortality in relation to smoking: 50 years' observation on male British doctors|year=2004|pmid=15213107|doi=10.1136/bmj.38142.554479.AE|journal=BMJ|volume=328|pages=1519|issue=7455|pmc=437139}}</ref>