Doll And Hill first computed the proposition that smoking was a risk factor for lung cancer in a case-control study (Doll and Hill, 1950). They found that, of 650 men having lung cancer (cases), 645 had smoked at some time, compared with 625 of the 650 men devoid of lung cancer (control).

Q1. Draw up a clearly labeled and appropriate 2 x 2 table to show such data.

Q2. How many times more probable was a smoker to develop lung cancer than a non-smoker?

Q3. Compute the proportion of lung cancers attributable to smoking among:

a) Smokers.
b) Whole population.

Q4. What is these measures termed and how does their interpretation vary?