Growth of Apple Trees from Different Root Stocks

Description

In a classic experiment carried out from 1918 to 1934, growth of apple trees of six different rootstocks were compared on four measures of size. How do the measures of size vary with the type of rootstock?

Format

A data frame with 48 observations on the following 5 variables.

rootstock

a factor with levels 1 2 3 4 5 6

girth4

a numeric vector: trunk girth at 4 years (mm x 100)

ext4

a numeric vector: extension growth at 4 years (m)

girth15

a numeric vector: trunk girth at 15 years (mm x 100)

weight15

a numeric vector: weight of tree above ground at 15 years (lb x 1000)

Details

This is a balanced, one-way MANOVA design, with n=8 trees for each rootstock.

Source

Andrews, D. and Herzberg, A. (1985). Data: A Collection of Problems from Many Fields for the Student and Research Worker Springer-Verlag, pp. 357–360.

References

Rencher, A. C. (1995). Methods of Multivariate Analysis. New York: Wiley, Table 6.2

Examples

library(car)
data(RootStock)
str(RootStock)

root.mod <- lm(cbind(girth4, ext4, girth15, weight15) ~ rootstock, data=RootStock)
car::Anova(root.mod)

pairs(root.mod)

# test two orthogonal contrasts among the rootstocks
hyp <- matrix(c(2,-1,-1,-1,-1,2,  
                1, 0,0,0,0,-1), 2, 6, byrow=TRUE)
car::linearHypothesis(root.mod, hyp)
heplot(root.mod, hypotheses=list(Contrasts=hyp, C1=hyp[1,], C2=hyp[2,]))

heplot1d(root.mod, hypotheses=list(Contrasts=hyp, C1=hyp[1,], C2=hyp[2,]))