Poisson frequency distribution as a function of X Î {int 0 ...¥}
P(X) = P(X-1) m/X = mx e-m/ X! s2 = m
n large & p small ® P(X) @ B(X) m = np
For example, estimating the expected number of positives
in a given sized library of cDNAs, genomic clones,
combinatorial chemistry, etc. X= # of hits.