[R] Which skewness does pelpe3() from package "lmom" use?
frauke
fhoss at andrew.cmu.edu
Fri Aug 16 23:19:00 CEST 2013
Hi everyone,
I was trying to fit a Log Pearson III distribution through some maxima data.
I got thrown off because my results in Excel (using a frequency factor
table) are different from my results using pelpe3() in the R-package "lmom".
The only reason I can think of is the skewness.
The Pearson III distribution has three parameters: Location (mean), scale
(standard deviation) and shape (skewness). The command pelpe3() returns the
same values for the first two parameters like I had computed in Excel.
However, the skewness is much higher.
Excel uses the type II skewness. *Does anybody know what type of skewness
pelpe3() uses and why?*
To be complete, I included some data.
data.txt <http://r.789695.n4.nabble.com/file/n4673984/data.txt>
This table gives the the maximum daily rainfall for each of 22 years. I want
to fit the distribution through those maximum rainfall events. These are the
parameters that I generated for the Pearson III distribution in Excel and R:
* Excel R*
*location (mean) * 0.68 0.68
*shape (skewness) *1.04 *1.6*
*scale (stand dev)* 0.38 0.4
Any help would be greatly appreciated!
Thank you!
Frauke
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