Making Sense of Statistics for Family Practitioners

Despite these challenges, casecontrol studies are relatively inexpensive, small to conduct, of short duration and the control groups are readily available for comparison within the same study base. Doll R et al compared mortality in relation to cigarette smoking among smokers and nonsmokers in the UK over a fifty year period.1 Although the study spanned a period of fifty years, it was relatively easy to collect data on causes of death in 98.9% of cases (cigarette smokers), controls (non-cigarette smokers), and correlated exposure to cigarette smoking. The most significant finding was that men from the same cohort born in 1900 ‐ 1930 who smoked only cigarettes and