####### This R-code is for creating Figure 23.

	set.seed(100)
	
	x1 <- seq(1,95)/190
	x2 <- c(52,64,76,85,95)/100
	x  <- c(x1,x2)
	xx <- seq(1,100)/100
	f  <- 1+xx+xx^2
	y  <- 1+x+x^2+rnorm(100,0,1)*0.2
	ker<- (exp(-(x-0.5)^2/0.02))/sqrt(2*pi)
	kfit <- sum(y*ker)/sum(ker)

	pdf("fig23.pdf",width=7.5,height=4)

	par(mfrow=c(1,2),mar=c(4,4,1,0))
	
	plot(x,y,type="p",xlab="",ylab="",xaxt="n",yaxt="n",
	ylim=c(0,3.5),mgp=c(2,1,0),cex=0.4)
	axis(1,at=c(0.2,0.5,0.8),lab=expression(x-h[n]/2,x,x+h[n]/2),
	     cex=0.9)
	axis(2,at=c(kfit),lab=expression(widehat(f)[NW](x)),cex=0.9)
	lines(xx,f,lty=1)
	lines(xx[21:80],rep(kfit,length(x[39:98])),lty=2,lwd=2)
	lines(rep(0.2,20),seq(0,19)/6,lty=3)
	lines(rep(0.5,20),seq(0,19)/6,lty=3)
	lines(rep(0.8,20),seq(0,19)/6,lty=3)
	lines(x[39:98],ker[39:98],lty=1)
	title(xlab="(a)",cex=1)

	fit1 <- lm(y[39:98]~x[39:98])

	plot(x,y,type="p",xlab="",ylab="",xaxt="n",yaxt="n",
	ylim=c(0,3.5),mgp=c(2,1,0),cex=0.4)
	axis(1,at=c(0.2,0.5,0.8),lab=expression(x-h[n]/2,x,x+h[n]/2),
	     cex=0.9)
	axis(2,at=c(fit1$fitted.values[57]),
	     labels=expression(widehat(f)[LK](x)),cex=0.9)
	lines(xx,f,lty=1)
	lines(x[39:98],fit1$fitted.values,lty=2,lwd=2)
	lines(rep(0.2,20),seq(0,19)/6,lty=3)
	lines(rep(0.5,20),seq(0,19)/6,lty=3)
	lines(rep(0.8,20),seq(0,19)/6,lty=3)
	lines(x[39:98],ker[39:98],lty=1)
	title(xlab="(b)",cex=1)
	
	graphics.off()