# Talk:Poisson distribution

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## Waiting time to next event.

In the waiting time to the next event

${\displaystyle P(T>t)=P(N_{t}=0)=e^{-\lambda t}.\,}$

This looks like it isn't normarmalized. since there should be a ${\displaystyle \lambda }$ out in front. Am I wrong? Pdbailey 03:47, 11 Jan 2005 (UTC)

Yes; you're wrong. The normalizing constant should appear in the probability density function, but not in this expression, which is 1 minus the cumulative distribution function. Michael Hardy 03:50, 11 Jan 2005 (UTC)

## Erlang Distribution

There's a refrence to erlang distribution, but the article does not mention the mutual dependence between Erlang Distribution and Poission Distribution. That is, the number of occurrences within a given interval follows a Poission distribution iff the time between occurrences follows an exponential distribution. (unsigned by user:Oobyduby)

## Do we need the "Computer software for the Poisson distribution" section?

Do we need the "Computer software for the Poisson distribution" section? Realistically it is a very common distribution and effectively any generic statistical computing package will include this functionality. As it article stands there is little reason not to add MATLAB, SAS or even C (through some C external library akin to SciPy, like GSL) examples. Just something like: "Poisson distributed random variables can be readily generated in R, Excel, Mathematica, SAS, Python (SciPy), MATLAB, C/C++ (GSL), etc. ..." should be adequate. — Preceding unsigned comment added by Homo Ex Machina (talkcontribs) 00:23, 23 March 2017 (UTC)