[R] MLE for lambda of Poisson distribution using fitdistr
Peter Ehlers
ehlers at ucalgary.ca
Tue Oct 27 15:15:31 CET 2009
Kjetil Halvorsen wrote:
> What is wrong with using
> mean(x)
> to get the MLE of the poisson lambda?
>
and
mean(x)/length(x)
to get its estimated variance.
-Peter Ehlers
> Kjetil
>
> On Tue, Oct 27, 2009 at 9:17 AM, David Winsemius <dwinsemius at comcast.net> wrote:
>> On Oct 26, 2009, at 11:25 PM, ankush2kn at yahoo.com wrote:
>>
>>> Hi,
>>>
>>> I am using the fitdistr of MASS to get the MLE for the lambda of a Poisson
>>> distribution.
>>> When i run the fitdistr command, i get an output that looks like -
>>>
>>> lambda
>>> 3.750000
>>> (0.03343)
>>>
>>> Couple of questions -
>>> 1. is the MLE 0.03343 for the lambda of the given distribution then?
>>> 2. How would I calculate the variance of the MLE for the lambda?
>> It would be more typical statistical usage to have output of the form:
>> estimate ( se(estimate) ) .... so I was expecting 3.75 to be the estimate.
>> Looking at the help page and running str(.) on the fitdistr object of the
>> first example confirms my expectations. Why did you think the help page was
>> suggesting otherwise?
>>
>> --
>>
>> David Winsemius, MD
>> Heritage Laboratories
>> West Hartford, CT
>>
>> ______________________________________________
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>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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