#
# Epage 137
#
# Written by:
# -- 
# John L. Weatherwax                2009-04-21
# 
# email: wax@alum.mit.edu
# 
# Please send comments and especially bug reports to the
# above email address.
# 
#-----

# version$language == "R" for R version$language == NULL for SPlus

if(is.null(version$language) == FALSE) require(alr3) else library(alr3)

if(is.null(version$language) == FALSE) data(domedata)

if(is.null(version$language) == FALSE)
   pairs(domedata,gap=0.4,cex.labels=1.5,cex=0.5)  else
   pairs(domedata)

attach(domedata)

D <- factor( Cond, ordered=FALSE )

m1 <- lm( Dist ~ Velocity + Angle + BallWt + BallDia + D ) # the most general model
m2 <- lm( Dist ~ Velocity + Angle + BallWt + BallDia     ) # remove the factor
m3 <- lm( Dist ~ Velocity + Angle                        ) # remove some properites of the ball
m4 <- lm( Dist ~ Velocity + Angle                    + D ) # remove some properites of the ball but add back in the factor
#m5 <- lm( Dist ~ D ) 

dgts <- 3 

print( c(m1$df.residual, sum( residuals(m1,type="pearson")^2 )), digits=dgts ) 

# compare all models to the most general model (model 1):
#
a2<-anova(m2,m1)
print( c( a2$Res.Df[1], a2$RSS[1], a2$F[2], a2$'Pr(>F)'[2] ), digits=dgts ) 

a3<-anova(m3,m1)
print( c( a3$Res.Df[1], a3$RSS[1], a3$F[2], a3$'Pr(>F)'[2] ), digits=dgts )

a4<-anova(m4,m1)
print( c( a4$Res.Df[1], a4$RSS[1], a4$F[2], a4$'Pr(>F)'[2] ), digits=dgts )