pdf("C:\\Rmisc\\rpd.prob.1.9a.pdf")

x <- c(29.7,68.4,120.7,217.2,313.5,419.1,535.9,641.5)
y <- c(16.6,49.1,121.7,219.6,375.5,570.8,648.2,755.6)

xy <- data.frame(x,y)

attach(xy)

xy    # print the xy dataframe

xy.reg <- lm(y~x)    # Fit the regression (lm=linear model)
summary(xy.reg)      # Print out estimates, t-tests
anova(xy.reg)        # Print out ANOVA table


xy.reg0 <- lm(y~x -1)  #  Fits regression thru Origin
summary(xy.reg0)      # Print out estimates, t-tests
anova(xy.reg0)        # Print out ANOVA table


plot(x,y,xlab="Solar Radiation",ylab="Plant Biomass",main="RPD-Problem 1.9",
  xlim=c(0,675),ylim=c(-100,900))
abline(xy.reg,lty=1)
abline(xy.reg0,lty=2)

dev.off()