[R] distribution freq
murdoch.duncan at gmail.com
Fri Feb 26 13:41:47 CET 2016
On 26/02/2016 4:09 AM, catalin roibu wrote:
> I'm working in forestry research and need the fitting distribution for
> forest structure in relation with diameter.
> The tree diameter have been lumped into 4 cm diameter classes, forming the
> diameter experimental distribution.
> For fitting I used the gamma distribution and I obtained the distribution
> parameters (scale and rate). After that I used the dgamma function and I
> have the pdf values. My question is how to obtain fitted absolute frequency
> to compare with the true frequency?
Since you're lumping into classes, you don't want the density, you want
differences in the cumulative probability. So if your class runs from 4
to 8 cm, use something like
pgamma(8, shape, rate) - pgamma(4, shape, rate)
or the equivalent but a little obscure
diff(pgamma(c(8, 4), shape, rate))
P.S. Please keep discussion on the mailing list. I've cc'd this
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