#  TO DRAW BETA(19,4) PRIOR in R:

par(lwd=1.5,cex=1.5,mar=c(5,4,1,1))

x<-seq(0,1,length=101)
plot(x,dbeta(x,19,4),type="l",
  xlab=as.expression(as.name('theta')),ylab="density",cex=1.5)