Using techniques from an earlier section, we can find a confidence Interval for / Consider a random sample of n matched data pairs A, B. Let d = 8 - A be a random variable representing the difference between the values in a matched data pair, Compute the sample mean d of the differences and the sample standard deviation s If d has a normal distribution or Is mound-shaped, or if n 2 30, then a confidence interval for . is as follows. d - Ecusd+E where E = c = confidence level (0