Researchers want to see if diet, exercise, or both are effective in combating insomnia. One hundred volunteers suffering from insomnia agreed to participate in a month-long test. Half were randomly assigned to a special no-desserts diet while the other half continued to eat desserts as usual. Half of the people in each of these groups were randomly assigned to an exercise program, while the others did not exercise. The researchers recorded the number of hours each participated slept for each night of a month. At the end of the month, the total number of sleep hours for each participant were compared.

1. What is the response variable?

1. What is the explanatory variable?

1. What are the treatments?

1. Does this experiment implement the Four Principles of Experimental Design? Why or why not?