"trees" <-
data.frame(Girth = c(8.3, 8.6, 8.8, 10.5, 10.7, 10.8, 11, 11, 11.1,
11.2, 11.3, 11.4, 11.4, 11.7, 12, 12.9, 12.9, 13.3, 13.7, 13.8, 14, 14.2,
14.5, 16, 16.3, 17.3, 17.5, 17.9, 18, 18, 20.6), Height = c(70, 65, 63,
72, 81, 83, 66, 75, 80, 75, 79, 76, 76, 69, 75, 74, 85, 86, 71, 64, 78,
80, 74, 72, 77, 81, 82, 80, 80, 80, 87), Volume = c(10.3, 10.3, 10.2, 16.4,
18.8, 19.7, 15.6, 18.2, 22.6, 19.9, 24.2, 21, 21.4, 21.3, 19.1, 22.2, 33.8,
27.4, 25.7, 24.9, 34.5, 31.7, 36.3, 38.3, 42.6, 55.4, 55.7, 58.3, 51.5,
51, 77))