S2: Normal Approximation to a Poisson

[JazzMan]

What is the critical value of λ when approximating a Poisson to a normal distribution. I tend to use λ≥20 but I have come across questions which say using a suitable approximation and λ has been less than 20.

I wondered if there was a standard value.

[DaveD]

I go with the context of the question. If it says use a suitable approximation then go with the given value of λ. I have used values as low as 15