Head measurements of football players

Description

Data collected as part of a preliminary study examining the relation between football helmet design and neck injuries. There are 30 subjects in each of three groups: High school football players, college players and non-football players.

Format

A data frame with 90 observations on the following 7 variables.

group

a factor with levels High school College Non-football

width

a numeric vector: head width at widest dimension

circum

a numeric vector: head circumference

front.back

a numeric vector: front to back distance at eye level

eye.top

a numeric vector: eye to top of head

ear.top

a numeric vector:ear to top of head

jaw

a numeric vector: jaw width

Source

Rencher, A. C. (1995), Methods of Multivariate Analysis, New York: Wiley, Table 8.3.

Examples

data(FootHead)
str(FootHead)
require(car)

# use Helmert contrasts for group
contrasts(FootHead$group) <- contr.helmert
contrasts(FootHead$group)

foot.mod <- lm(cbind(width, circum,front.back,eye.top,ear.top,jaw) ~ group, 
               data=FootHead)
Manova(foot.mod)

# show the HE plot for the first two variables
heplot(foot.mod, main="HE plot for width and circumference", fill=TRUE,
	col=c("red", "blue"))

# show it with tests of Helmert contrasts
heplot(foot.mod, hypotheses=list("group.1"="group1","group.2"="group2"),
	col=c("red", "blue", "green3", "green3" ),
	main="HE plot with orthogonal Helmert contrasts")

# show all pairwise HE plots
pairs(foot.mod)

# ... with tests of Helmert contrasts
pairs(foot.mod, hypotheses=list("group.1"="group1","group.2"="group2"),
	col=c("red", "blue", "green3", "green3"), hyp.labels=FALSE)

# see that the hypothesis for groups really is 2D
if(requireNamespace("rgl")){
heplot3d(foot.mod, variables=c(1,2,6),
	hypotheses=list("group.1"="group1","group.2"="group2"),
	col=c("red", "blue", "green3", "green3" ), wire=FALSE)
}