Question

A study was done to compare the lung capacity of

coal miners to the lung capacity of farm workers. The

researcher studied 200 workers of each

type. Other factors that might affect lung capacity are smoking habits and exercise habits. The

smoking habits of the two worker types are similar, but the coal miners generally exercise less

than the farm workers.

1. Which of the following is the explanatory variable in this study?

a. Exercise

b. Lung capacity

c. Smoking or not

d. Occupation

Statistics and Probability