If a set of n = 9 difference scores has a mean of M_D = 3.5 and a variance of s² = 36,then the standard error for the sample mean difference is 4 points.

Question

Quizplus · Accepted Answer

The formula for the standard error of the mean for a set of scores is: SEM = s / sqrt(n) where s is the standard deviation of the scores and n is the sample size. In this case, we are given the variance (s^2) instead of the standard deviation, so we need to take the square root of the variance first to get s: s = sqrt(s²) = 6 Substituting this value and the sample size (n = 9) into the formula gives: SEM = 6 / sqrt(9) = 6 / 3 = 2 Therefore, the standard error for the sample mean difference is 2 points, not 4 points, so the correct answer is B.

If a Set of N = 9 Difference Scores Has