Error in Poisson's distribution.

have some example data, trying to use poisson's PDF, (this is a small part of the overall code) but keep getting a error of. Any ideas where i've gone wrong. I can get Weibull pdf & Gamma pdf to work using the same process.

??? Attempted to access paramEsts(2); index out of bounds because numel(paramEsts)=1.
  Error in => fix at 4
  pdfEst = poisspdf(xgrid,paramEsts(1),paramEsts(2));

Data = [15 6 7 3 4 9 6 1 1 2 3 4 5 9 7 7 7 5 1 1];                                    
xgrid = linspace(0,20);                                                    
paramEsts = poissfit(Data);                                                
pdfEst = poisspdf(xgrid,paramEsts(1),paramEsts(2));

Answer 1

[Roger Stafford]

As you have written it, 'paramEsts' will be a single scalar consisting of the maximum likelihood estimate of the Poisson parameter. That is the reason paramEsts(2) does not make sense. Here is a quote from the poissfit documentation: "lambdahat = poissfit(data) returns the maximum likelihood estimate (MLE) of the parameter of the Poisson distribution, λ, given the data data."

[harley]

thanks Roger, any suggestions on how i should correctly write it.

[Roger Stafford]

I'm not sure what you expect. What is wrong with writing just this:

 paramEsts = poissfit(Data);
 pdfEst = poisspdf(xgrid,paramEsts);

I see no evidence in your stuff for a second parameter value for 'poisspdf'. In any case, the second argument of 'poisspdf' will either have to be a scalar or else a vector the same size as 'xgrid' to satisfy 'poisspdf' requirements.