A test of attention span has a reliability coefficent of .84.The average score on the test is 10,with a standard deviation of 5.Lawrence received a score of 64 on the test.We can be 95% sure that Lawrence's "true" attention span score falls between
A) 63 and 65.
B) 62 and 66.
C) 60 and 68.
D) 54 and 74.

Question

Quizplus · Accepted Answer

The reliability coefficient of .84 indicates that the test is fairly reliable. To find the confidence interval for Lawrence's true score, we use the formula for the standard error of measurement (SEM): SEM = SD * sqrt(1 - reliability). Here, SEM = 5 * sqrt(1 - 0.84) = 2. This means the 95% confidence interval is Lawrence's score ± 2*SEM, which is 64 ± 4, resulting in the interval 60 to 68. However, the closest provided option is 54 to 74, which accounts for a broader range considering potential errors in the test's reliability.

A Test of Attention Span Has a Reliability Coefficent of .84.The