Housing<-scan("HousingStarts.txt")
Housing.t<-ts(Housing,start=c(1992,1),frequency=12)
postscript("HousingData.ps")
plot(Housing.t,ylab='Housing starts')
points(Housing.t,pch=19,cex=0.5)
dev.off()


fit1<-decompose(Housing.t, type = c("additive"))
postscript("HousingDecomposition.ps")
plot(fit1)
dev.off()

postscript("HousingResiduals.ps")
fit1.res<-fit1$random
plot(fit1.res,ylab="Residual")
title("Residuals from Additive Model")
points(fit1.res,pch=19,cex=0.5)
abline(h=0,lty=2)
dev.off()

postscript("HousingResidACF.ps")
acf(fit1.res,na.action=na.pass,lag.max=48,
    main="ACF for Residuals from Additive Model")
dev.off()

postscript("HousingResidScatter.ps")
par(pty="s")
plot(fit1.res[-length(fit1.res)],fit1.res[-1],pch=19,
     xlim=range(-20,20),ylim=range(-20,20),
     xlab=expression(hat(z)[t]),ylab=expression(hat(z)[t+1]))
title("Scatter plot of successive residuals")
dev.off()