Exercise 9.6.1 Sulzberger (1953) andWilliams (1959) examined themaximum compressive strength parallel to the grain (y) of 10 hoop trees and howitwas affected by temperature.Acovariate, the moisture content of thewood (x),was alsomeasured.

Analyze the data, which are reported below Temperature in Celsius −20 0 20 40 60 Tree y x y x y x y x y x 1 13.14 42.1 12.46 41.1 9.43 43.1 7.63 41.4 6.34 39.1 2 15.90 41.0 14.11 39.4 11.30 40.3 9.56 38.6 7.27 36.7 3 13.39 41.1 12.32 40.2 9.65 40.6 7.90 41.7 6.41 39.7 4 15.51 41.0 13.68 39.8 10.33 40.4 8.27 39.8 7.06 39.3 5 15.53 41.0 13.16 41.2 10.29 39.7 8.67 39.0 6.68 39.0 6 15.26 42.0 13.64 40.0 10.35 40.3 8.67 40.9 6.62 41.2 7 15.06 40.4 13.25 39.0 10.56 34.9 8.10 40.1 6.15 41.4 8 15.21 39.3 13.54 38.8 10.46 37.5 8.30 40.6 6.09 41.8 9 16.90 39.2 15.23 38.5 11.94 38.5 9.34 39.4 6.26 41.7 10 15.45 37.7 14.06 35.7 10.74 36.7 7.75 38.9 6.29 38.2