Bill was about to graduate from college when he crashed car and suffered a head injury. Shortly before the crash, he had scored 130 on an IQ test given by a career counselor. Now on the same test his score is 110. The test has a mean of 100, standard deviation of 10, and test-retest reliability of .75. Do you think it is likely his post score reflects a real difference or is due to measurement error? Show your reasoning, including the SEM and confidence intervals on Bill's initial test.