Clustering and Poisson distributions

[MalignD at aol.com]

In an article about disease clusters in today's Sunday Times, Week in Review,
one Dr. Persi Diaconis, a statistician at Stanford, regarding clusters
appearing even in random events, was quoted:

"'There was a famous example of this when bombs were hitting London during
World War II,' [Dr. Diaconis] said. 'People were sure they were targeting
individual places and they made up the most elaborate scenarios' to explain
how the bomb targets were selected.  But in the end, when the pattern was
analyzed, the bombing turned out to be random."