| % File src/library/datasets/man/trees.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2018 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{trees} |
| \docType{data} |
| \alias{trees} |
| \title{Diameter, Height and Volume for Black Cherry Trees} |
| \description{ |
| This data set provides measurements of the diameter, height and volume |
| of timber in 31 felled black cherry trees. Note that the diameter (in inches) is erroneously |
| labelled Girth in the data. It is measured at 4 ft 6 in above the ground. |
| } |
| \usage{trees} |
| \format{ |
| A data frame with 31 observations on 3 variables. |
| \tabular{rlll}{ |
| \code{[,1]} \tab \code{Girth} \tab numeric |
| \tab Tree diameter (rather than girth, actually) in inches\cr |
| \code{[,2]} \tab \code{Height}\tab numeric |
| \tab Height in ft\cr |
| \code{[,3]} \tab \code{Volume}\tab numeric |
| \tab Volume of timber in cubic ft\cr} |
| } |
| \source{ |
| Ryan, T. A., Joiner, B. L. and Ryan, B. F. (1976) |
| \emph{The Minitab Student Handbook}. |
| Duxbury Press. |
| } |
| \references{ |
| Atkinson, A. C. (1985) |
| \emph{Plots, Transformations and Regression}. |
| Oxford University Press. |
| } |
| \examples{ |
| require(stats); require(graphics) |
| 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 |
| } |
| \keyword{datasets} |