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()

Making Venn Diagrams

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

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