13.83 At the beginning of last year, a power company asked each of its industrial customers to estimate how much electricity it would require during the year. At the end of the year, the power company recorded the extent to which a customer’s estimate was over or under the amount of electricity actually used. In data file XR13083, customers are described according to their size (1 5 small, 2 5 medium, 3 5 large) and the extent to which their usage differed compared to their estimate (1 5 used more than 110% of estimate, 2 5 within 10% of estimate, and 3 5 used less than 90% of estimate). At the 0.025 level of significance, test whether customer size might be independent of estimation accuracy.