Using an independent-measures t,the 90% confidence interval for the difference between two population means ranges from 19 to 23.Based on this confidence interval,how big is the difference between the two sample means?
A)4 points
B)19 points
C)21 points
D)23 points

Question

Quizplus · Accepted Answer

Since the confidence interval for the difference between the two population means ranges from 19 to 23, we can assume that the point estimate of the difference between the two sample means is at the center of this interval. Therefore, the difference between the two sample means would be (23-19)/2 = 2 points away from the midpoint of the interval, which is 21. Thus, the best choice is C) 21 points.

Using an Independent-Measures T,the 90% Confidence Interval for the Difference