From: "R. Michael Weylandt" <michael.weylandt at gmail.com>
Sent: Nov 3, 2011 10:39 PM
To: Steve_Friedman at nps.gov
Cc: r-help at r-project.org
Subject: Re: [R] Plotting skewed normal distribution with a bar plot
It seems like you'll need to apply some sort of MLE to estimate the
parameters directly from the data before using dsn() to get the
density. This might help with some of it:
http://help.rmetrics.org/fGarch/html/snorm.html
Michael
On Thu, Nov 3, 2011 at 2:54 PM, <Steve_Friedman at nps.gov> wrote:
Hi,
I need to create a plot (type = "h") ?and then overlay a skewed-normal
curve on this distribution, but I'm not finding a procedure to accomplish
this. I want to use the plot function here in order to control the bin
distributions.
I have explored the sn library and found the dsn function. ?dsn uses known
location, scaling and shape parameters associated with a given input vector
of probabilities. ?However, how can I calculate the skewed-normal curve if
I don't know these parameters in advance?
Is there another function to calculate the skew-normal, perhaps in a
different package?
I'm working with R 2.13.2 on a windows based machine.
Steve Friedman Ph. D.
Ecologist ?/ Spatial Statistical Analyst
Everglades and Dry Tortugas National Park
950 N Krome Ave (3rd Floor)
Homestead, Florida 33034
Steve_Friedman at nps.gov
Office (305) 224 - 4282
Fax ? ? (305) 224 - 4147