# Example 3.3 (Table 3.3) in Davis, 2002; Orthodont data in Pinheiro & Bates

age <- c(8,10,12,14)
m <- matrix(scan("e:\\vhm\\vhm882\\data\\pr.dat"),ncol=6,byrow=T)
sex <- m[,1]
subject <- m[,2]
y <- m[,3:6]

# code for graphics, using nlme and lattice libraries
library(nlme)
data(Orthodont)
plot(Orthodont)
# mean plot
Ortho.means <- aggregate(Orthodont$distance,list(Orthodont$age,Orthodont$Sex),mean,na.rm=TRUE)
names(Ortho.means)[1]<-"Age"
Ortho.means$Age <- as.numeric(levels(Ortho.means$Age))[Ortho.means$Age]
names(Ortho.means)[2]<-"Sex"
library(lattice)
xyplot(x~Age|Sex,Ortho.means,ylab="Mean distance from pituitary to pt. fissure (mm)")

# test for equality between boys and girls
summary(manova(y~sex))

# test for parallel curves
diff <- matrix(c(y[,1]-y[,2],y[,2]-y[,3],y[,3]-y[,4]),nrow=27,ncol=3,byrow=FALSE)
summary(manova(diff~sex))