[BioC] How to do poisson distribution test like this?

[Michael Dondrup]

Dear Mao,
I don't know about the particular setting but here's a simple approach:

 > ppois(q=35,lambda=30, lower=F)
[1] 0.1573835
gives the probability of observing 36 or more events from a Poisson  
distributed random variable with mean 30 (aka expected number of genes).
Does not give you the exact figure (0.137) though.

Best
Michael

Am 28.07.2009 um 12:06 schrieb Mao Jianfeng:

> Dear Bioconductor-listers,
>
> I want to reperfrom a poisson distribution test that was presented  
> in a
> recent-published biological research paper (Plant Physiology 2008,  
> vol 148,
> pp. 1189-1200). That test is about the occurrence number of a kind  
> of gene
> in separate chromosomes.
>
> For instance:
>
> The observed gene number in chromosome A is 36.
> The expected gene number in chromosome A is 30.
>
> Then, the authors got a probability 0.137 by distribution test on this
> trial. In this test, a Poisson distribution was used to determine the
> significance of the gene distribution.
>
> Questions:
>
> How can I reperform this test in R?
>
> Thank you in advance.
>
> Mao Jian-Feng
> Institue of Botany,
> CAS, China
>
> 	[[alternative HTML version deleted]]
>
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Michael Dondrup, Ph.D.
Bergen Center for Computational Science
Computational Biology Unit
Unifob AS - Thormøhlensgate 55, N-5008 Bergen, Norway