Exercise 9.6.1 Sulzberger (1953) and Williams (1959) examined the maximum compressive strength parallel to the grain (y) of 10 hoop trees and how it was affected by temperature. A covariate, the moisture content of the wood (x), was also measured. 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