You are planning a case-control study of lung cancer to test the hypothesis that vegetable consumption is protective against lung cancer. would you match on smoking? explain your answer.

The answer is yes.

Explanation:

Due to the fact that a very high percentage of lung cancer develops in people who had smoked, it should be necessary to include also the main cause of this cancer in the study of a factor that can prevent or avoid it. If one of the main causes is also, for example, genetics, then it should be also considered in the study.