Re: [igraph] community detection significance

[Gang Su]

I thought the modularity score is already a comparison to a null model?

Best wishes,

Gang Su

Bioinformatics PhD candidate
Statistics MA
University of Michigan, Ann Arbor
Michigan 48109


On Thu, Jun 14, 2012 at 3:02 PM, Tamás Nepusz <address@hidden> wrote:
>> What exactly is "community significance"? Any literature? --Moses
>
> Start here, these papers are open access and relatively recent:
>
> [1] http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0018961
> [2] http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0033721
>
> --
> T.
>>
>> On Thu, Jun 14, 2012 at 9:58 PM, Tamás Nepusz <address@hidden 
>> (mailto:address@hidden)> wrote:
>> > Dear Filipe,
>> >
>> > None of the community significance algorithms are implemented in igraph 
>> > yet and I am not aware of any such implementations yet. A relatively 
>> > simple approach is to take each vertex in the community, calculate their 
>> > internal and external degrees (i.e. the number of edges incident on them 
>> > that lead inside the community and outside the community, respectively), 
>> > and then run a Mann-Whitney U-test. The null hypothesis is that the 
>> > distribution of internal and external degrees is the same (in other words, 
>> > the community is not a real one because it is just as dense "inside" as 
>> > "outside"), and the test will reject it if the community is a significant 
>> > one. I'm sure that there are far better methods than this, but this is 
>> > relatively easy to implement both in R and in Python using igraph.
>> >
>> > Best,--
>> > T.
>> >
>> >
>> > On Thursday, 14 June 2012 at 20:55, Filipe Alberto wrote:
>> >
>> > > Dear list,
>> > >
>> > > I have been using igraph to detect communities in networks. However, I 
>> > > would like to use some method to get significance of the derived 
>> > > communities. I see that there are several algorithms published, but I 
>> > > don't know if they are available in igraph or if some of the users have 
>> > > implemented them using R and igraph?
>> > >
>> > >
>> > > Thanks you for your help,
>> > >
>> > > All the best,
>> > > Filipe Alberto
>> > >
>> > > _______________________________________________
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>> >
>> >
>> >
>> >
>> >
>> >
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