
In your example it appears that you are plotting a histogram (on the 
frequency
scale) and then superimposing scalar multiples of gamma and Gaussian 
densities.

You should just plot a histogram (with frequency=FALSE) and then 
superimpose the
densities --- without any scalar multipliers.

If that doesn't work, please provide a minimal *reproducible* (no one 
but you
has the ``rwb'' data object) example of the problem that you are having
(as the posting guide requests).

     cheers,

         Rolf Turner


On 16/05/11 17:01, Benjamin Caldwell wrote:
> Hmm; still missing something - hist defaults to frequencies, not prob. 
> densities; and, I thought I'd scaled the fitted lines to the values in 
> the data frame. Just going with it, I specified freq=FALSE, and the 
> prob density was of course at a different order of magnitude than the 
> lines.
>
> What are you trying to hint at?
>
>
> On Fri, May 13, 2011 at 6:05 PM, Rolf Turner <rolf.turner@xtra.co.nz 
> <mailto:rolf.turner@xtra.co.nz>> wrote:
>
>     On 14/05/11 10:00, Benjamin Caldwell wrote:
>
>         Hello,
>
>         I'm trying to compare the fit of two distributions, normal and
>         gamma, to a
>         histogram of my response variable.
>
>         rate<-mean(na.omit(rwb$post.f.crwn.length))/var(na.omit(rwb$post.f.crwn.length))
>         shape<-rate*mean(na.omit(rwb$post.f.crwn.length))
>         hist((rwb$post.f.crwn.length), main="rwb$post.f.crwn.length")
>         lines(seq(0.01,70,0.01),length(rwb$post.f.crwn.length)*dgamma(seq(0.01,70,0.01),shape,rate))
>         lines(seq(0,70,0.1),length(na.omit(rwb$post.f.crwn.length))*dnorm(seq(0,70,.1),mean(na.omit(rwb$post.f.crwn.length)),sqrt(var(na.omit(rwb$post.f.crwn.length))))
>
>         However, the height of the two curves are about 1/3 to 1/4 the
>         height that
>         they should be compared to the histogram. Any ideas?
>
>
>     Yes.  Read the help on "hist"!  (Hint:  Pay particular attention
>     to the
>     "freq" and/or "probability" arguments.)
>
>        cheers,
>
>            Rolf Turner
>
>


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