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Re: [igraph] errors using power.law.fit

From: Gábor Csárdi
Subject: Re: [igraph] errors using power.law.fit
Date: Tue, 16 Nov 2010 11:24:59 +0100

On Tue, Nov 16, 2010 at 11:20 AM, Tamas Nepusz <address@hidden> wrote:
> But actually, I was stupid, the authors of that paper have a working
> R code here:
> http://tuvalu.santafe.edu/~aaronc/powerlaws/
>> Also, the article seems to imply - in the recipe part - that you
>> estimate the alpha and Xmin parameters, and then test with the
>> Kolmorgov Smirnov test for goodness of fit. Now, this implies that I
>> still may run into troubles with the optim() error I got our of R.
> Apparently not, the R code linked above does not use optim(), it uses
> some other calculation that seems to give a MLE of alpha given xmin
> using an exact formula.

Which is quite surprising, because there is no exact formula for
discrete data AFAIK. IMHO the formula in the appendix of the Newman
paper works only for continuous data, it does not make sense to use it
for discrete data.


Gabor Csardi <address@hidden>     UNIL DGM

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