# Plot kernel density estimates of variable with normal curve:

plot.kdnc = function(v,...,xlab=deparse(substitute(v)),title="",rug=T)
{
  xlab=xlab
  v = na.omit(v)
  x = v
  dens=density(v,...)
  ylim=range(0,dnorm(x,mean=mean(v),sd=sd(v)),dens$y)
  if (title=="") title=paste("Kernel density estimates of",xlab,"\nwith normal curve")
  plot(dens,col='red',ylim=ylim,xlab=xlab,main=title)
  if (rug==T) rug(jitter(v),col="red")
  curve(dnorm(x,mean=mean(v),sd=sd(v)),col='blue',add=T)
}