Suppose a large population of test takers take the GMAT. You fear there may have been some cheating, so you ask those people who scored in the top 10% to take the exam again.
If their scores, on average, go down, is this evidence that there was cheating? Explain your answer.
If these same people were asked to take the test a third time, would you expect their scores to go down even further? Explain your answer.