# Thread: M.g.f for Poisson distribution

1. ## M.g.f for Poisson distribution

Hello,
I am having trouble understanding the maths between E() where I get a summation from 0 to and the m.g.f for Poisson distribution. The notes I have are to break out
(Now, don't get me wrong - I DO get how to make this last expression easier on the eye - It's just that breaking this out from the sum makes the sum go towards 1 as x approaches )
I can't seem to find what is supposed to be left in the summation nor why that would behave so nicely when the whole expression looks so strange (to me). I have been to (http://mathworld.wolfram.com/PoissonDistribution.html) and other resources, but my problem is not finding the mgf or using it but understanding how to get to it myself from the probability mass function.

2. ## Re: M.g.f for Poisson distribution

It is not difficult; You just need to know the series for exponential function
(or just the kernel of the Poisson distribution)

3. ## The Following User Says Thank You to BGM For This Useful Post:

Trillian (10-18-2012)

4. ## Re: M.g.f for Poisson distribution

going back to my calculus book again with new leads - Thank you!

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