[R] Finding Lambda in Poisson distribution

Matthias Kohl Matthias.Kohl at stamats.de
Mon Mar 2 19:58:14 CET 2009


assuming the assumption of Poisson distribution is true (or at least 
approximately true), you can use MLE as mentioned by Roland using 
(fitdistr of MASS, mle of stats4, MLEstimator of distrMod, probably more).

Using package distrMod you can compute minimum distance estimators (cf. 
function MDEstimator).

Using package ROptEst you can compute (in some sense) optimally robust 
estimators (cf. function roptest).


Rau, Roland wrote:
> Hi, 
>> -----Original Message-----
>> From: r-help-bounces at r-project.org 
>> [mailto:r-help-bounces at r-project.org] On Behalf Of Saeed Ahmadi
>> Sent: Monday, March 02, 2009 3:16 PM
>> To: r-help at r-project.org
>> Subject: [R] Finding Lambda in Poisson distribution
>> Hi,
>> I have a dataset. First of all, I know that my dataset shall 
>> follow the
>> Poission distribution. Now I have two questions:
>> 1) How can I check that my data follow the Poisson distribution?
>> 2) How can I calculate Lambda of my data?
> is this maybe some homework?
> For 2): I simulated data and did some simple MLE. I don't know if this
> is the recommended way, but it worked fine for me. 
> Best,
> Roland
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Dr. Matthias Kohl

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