Poisson Distribution

Question 1

What are the conditions required for a Poisson distribution? (4)

Answer 1

Conditions required for a Poisson distribution:

1. Events must occur singly in space or time
2. Events must occur independently of each other
3. Events must occur at a constant rate in the sense that the mean number of occurrences in the interval is proportional to the length of the interval
4. Such events must occur randomly

Question 2

When do you approximate a Binomial with a Poisson?

Answer 2

If X~B(n,p) and n is large and p is small, thenX can be approximated by Po(np)