treesf {Flury} | R Documentation |
Measurement on black cherry trees
data(treesf)
'treesf' is familiar data frame with observations on 31 trees with respect to the following 3 variables.
Diameter
Height
Volume
Note that the diameter needs to be coverted to feet (12 inches in 1 foot) before use. Assuming cone shaped trunks, the colume of wood available should be found from: V = (π/12) D^{2} H. By taking logarithms of the variables it is possible to fit log V = log(π/12) + 2 log D + log H by using lm().
Ryan, B.F., B. Joiner and T.A. Ryan (1976) Minitab Handbook (2nd edition) Boxton: Duxbury Press (page 278)
Flury, B.D. (1997) A First Course in Multivariate Statistics, Springer NY
data(treesf) ## Not run: Y <- log(treesf$Volume) X1 <- log(treesf$Diameter / 12) X2 <- log(treesf$Height) trees.lm <- lm(Y ~ X1 + X2) summary(trees.lm) log(pi/12) vcov(trees.lm) ## End(Not run)