Question

What experiment would you perform if you suspected that the number of hours of exercise had a causal influence on the average hours slept.

A.) Reduce subjects' food intake and observe the effect on sleep and exercise time

B.) Change the number of hours a subject exercises and observe the change in the average number of hours slept

C.) Change both the average number of hours a subject sleeps AND the number of hours they exercise and observe how both change.

D.) Change the average number of hours a subject sleeps, and observe the change in the number of hours of exercise.

Answer 1

Solution:

If we suspected that the number of hours of exercise had a causal influence on the average hours slept, then we would:

B.) Change the number of hours a subject exercises and observe the change in the average number of hours slept.

Explanation: As we want to know if the hours of exercise has a causal influence on the average hours slept, this implies that hours of exercise is the independent or the predictor variable here and the hours slept is the response or predicted variable.

Now when we want to know about the cause and effect relationship between two variables, we need not tamper with any third variable like food, here.

And if we change the values of both the variables simultaneously, then we cannot estimate the relationship.

Also since hours of exercise is our predictor variable, we shall change its values to see its effect on the hours of sleep and not vice versa.