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?

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.

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i those same problems in math and dont know how to do them