12.7 The paper “Cigarette Tar Yields in Relation to Mortality from Lung Cancer in the Cancer Prevention Study II Prospective Cohort” (British Medical Journal

[2004]: 72–79) included the accompanying data on the tar level of cigarettes smoked for a sample of male smokers who subsequently died of lung cancer.

Tar Level Frequency 0–7 mg 103 8–14 mg 378 15–21 mg 563

22 mg 150 Assume it is reasonable to regard the sample as representative of male smokers who die of lung cancer. Is there convincing evidence that the proportion of male smoker lung cancer deaths is not the same for the four given tar level categories?