Poisson Distribution

POISSON DISTRIBUTION

No. of events that occur random in an interval (of time or space)

X ~P_o ( l)

Events occur independently

“ “ singly Mean = E(X) = m= l

“ “ at a constant rate Variance = Var(X) = s² = l

Probability of r

P( X = r ) = e^-ll or use tables

r!

Approximation

Normal approx Þpoisson X ~P_o ( l) ÞX ~N (l, l)