Example 1 in this section illustrated the procedure for finding a prediction interval for an individual value of y. When using a specific value x0 for predicting the mean of all values of y, the confidence interval is as follows:

where

The critical value t_a/2 is found with n - 2 degrees of freedom. Using the 23 pairs of chocolate/Nobel data from Table 10-1 in the Chapter Problem, find a 95% confidence interval estimate of the mean Nobel rate given that the chocolate consumption is 10 kg per capita.

Table 10-1: