| trees {base} | R Documentation |
Girth, Height and Volume for Black Cherry Trees
Description
This data set provides measurements of the girth, height and volume of timber in 31 felled black cherry trees. Note that girth is the diameter of the tree (in inches) measured at 4 ft 6 in above the ground.
Usage
data(trees)Format
A data frame with 31 observations on 3 variables.
[,1] | Girth | numeric | Tree diameter in inches |
[,2] | Height | numeric | Height in ft |
[,3] | Volume | numeric | Volume of timber in cubic ft |
Source
Ryan, T. A., Joiner, B. L. and Ryan, B. F. (1976) The Minitab Student Handbook. Duxbury Press.
References
Atkinson, A. C. (1985) Plots, Transformations and Regression. Oxford University Press.
Examples
data(trees)
pairs(trees, panel = panel.smooth, main = "trees data")
plot(Volume ~ Girth, data = trees, log = "xy")
coplot(log(Volume) ~ log(Girth) | Height, data = trees,
panel = panel.smooth)
summary(fm1 <- lm(log(Volume) ~ log(Girth), data = trees))
summary(fm2 <- update(fm1, ~ . + log(Height), data = trees))
step(fm2)
## i.e. Volume ~= c * Height * Girth^2 seems reasonable