SOLUTION: Imagine that a psychologist wants to know if drinking coffee every day over the course of a semester can increase college students scores on the final exam in a statistics class.

Question 1075025: Imagine that a psychologist wants to know if drinking coffee every day over the course of a semester can increase college students scores on the final exam in a statistics class. He is able to get all the students in his class of 50 to agree to be a part of his study (unlikely I know - just go with it). He randomly assigns them to one of two groups. All students in Group 1 drink coffee before going to class every day. All students in Group 2 do not drink coffee before going to class. At the end of the semester, all of the students take the final exam. The students in Group 1 (coffee group) have a mean final exam score of 88. The students in Group 2 (no-coffee group) have a mean final exam score of 82. Give three possible explanations for the 6-point difference between the group means.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
1. There is no difference at all and each group is essentially the same sample, which would have a different mean of 6 points.
2. There is a difference, and it happens to be due to coffee.
3. There is a difference, and it doesn't have anything to do with coffee.

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