Consider a Study in Which Two Sets of 20 Mice

Essay

Consider a study in which two sets of 20 mice were given different amounts of caffeine in their drinking water. Members of the control group got none and members of the experimental group received 0.01% caffeine in their water. The number of minutes each mouse spent running on the wheel in their cage was measured over a series of 14 nights.
Describe why the appropriate sampling unit is the mean number of minutes for each of the 40 mice rather than the number of minutes during each of the 280 nights.
What are the sample sizes you would use when comparing this running data in the two groups?