Re: Continuous curve over barplot, corrected

[Sundar Dorai-Raj <sundar.dorai-raj@PDF.COM>]

David Parkhurst wrote:
> Duh.  A few minutes ago, I sent the wrong code, and what I sent does 
> work.  Thanks to those who told me so!
>  
> What I WANT to do (using Professional Edition Version 6.2.1  for 
> Microsoft Windows : 2003) is to plot  these dbinom values:
>  
> x<-60:100
> y<-dbinom(x,100,0.7)
> as a barplot, and then to overlay the normal densities below as a 
> continuous curve.  Any suggestions?
>  
> yy<-dnorm(x,70,sqrt(21))
> Thanks.
>  
> Dave Parkhurst
Dave,

Would the following work for you?

p <- 0.7
n <- 20
x <- 0:n
px <- dbinom(x, n, p)
z <- seq(min(x), max(x), length = 200)
pz <- dnorm(z, n * p, sqrt(n * p * (1 - p)))
barplot(px, x - 0.5, histo = TRUE, ylim = range(px, pz), col = 0)
lines(z, pz)

--sundar