statistics and probability

Using techniques from an earlier section, we can find a confidence interval for Ly. Consider a random sample of n matched data pairs A, B. Let d = B - 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 > 30, then a confidence interval for u is as follows. a - E