Doll And Hill first evaluated the proposition that smoking was a risk factor for lung cancer in a case-control study (Doll and Hill, 1950). They determine that, of 650 men with lung cancer (cases), 645 had smoked at some time, in comparison with the 625 of the 650 men without lung cancer (control).

a) Draw up a clearly labelled and appropriate 2 x 2 table to show these data.

b) How many times more likely was a smoker to develop lung cancer than a non-smoker?

c) Determine the proportion of lung cancers attributable to the smoking among:

 i) smokers and

ii) the whole population.

d) What are these measures known as and how does their interpretation differ?