From: Benjamin Caldwell <btcaldwell_at_berkeley.edu>

Date: Sun, 15 May 2011 22:01:50 -0700

R-help_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Mon 16 May 2011 - 05:06:04 GMT

Date: Sun, 15 May 2011 22:01:50 -0700

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_at_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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