#acl ChrisSeidel:read,write,delete,revert All:read
In making Venn diagrams to look at overlap of sets, I often wonder how significant a given amount of overlap is. What is the likelyhood of seeing a given amount of overlap from two sets, simply by chance?

One way to assess this, is to use the hypergeometric distribution. The R language has a nice function for calculating the p-value, but the explanation of how to use it involves an Urn of black and white balls.

{{{
phyper(q,m,n,k,lower.tail=F)
}}}
q = the number of white balls drawn from the urn (without replacement)

m = the number of white balls in the urn

n = the number of black balls in the urn

k = the number of balls drawn from the urn (sample size)

== Making Venn Diagrams ==
* I wrote a utility for making venn diagrams: [http://www.pangloss.com/seidel/Protocols/venn.cgi venn diagrams]

* But someone else wrote a better one recently: [http:// venny]