Question

After one month, Devon finds that his 10 friends slept an average of 0.5 hour more each night when they drank milk before bed. Based on this, Devon concludes that drinking milk makes teenagers sleepy. what is one reason why Devon's conclusion is most likely invalid?

Answer 1

He did not test it against anyone who did not drink milk before bed and he tested it on a relatively small number of people. In order to have more accurate results he should include more people in the study and should test it against the same number of people who haven't drank milk before bed. He should also take into account the amount of milk that they drank before going to bed.

Answer 2

No comparision and repeatibility

Explanation:

Firstly, this total number of hours each friend sleeps is not specified and therefore can vary each night. What is constant is that they drank milk before they slept and for one month the analysis was made. Secondly, he never made a comparison between milk drinkers and non-milk drinkers and therefore the analysis is just one sided and open to other effects such as exercise, eating habits etc. Furthermore, no repeatability was conducted to determine if the same results would be obtained. Lastly, the ages of the friends are unknown so making a conclusion of teenagers is inaccurate.