Poisson distribution

[Bramvs]

Dear ED community,

I've got a problem with the poison distribution. Trucks arrive every 4 hours and it takes 5 hours to unload them. When I enter 'poisson(hr(4))' in the interval arriving time of the source, the system crashes. Can someone help me with this?

Thank you in advance.

[MarvinH]

Hello!

First of all, please note that the Poisson distribution returns the (discrete random) number of arrivals during a certain time interval. The NegExp distribution returns the (continuous random) time between each of these arrivals.

For the relation between Poisson and (Negative) Exponential distribution, please refer to:
Poisson distribution
Exponential distribution

In your situation, you have a Poisson(6) distribution of trucks a day (inter-arrival time of 4 hours results in on average 6 trucks a day). The corresponding inter-arrival time between two trucks follows the NegExp(hr(4)) distribution. So when you want to model the inter-arrival time, you need to use the NegExp distribution. When you want to model the number of trucks during a particular time interval, you can use the Poisson distribution.

I will discuss the issue of the crashing system with the development team.

Good luck!

Kind regards,

Marvin

[Bramvs]

Thank you for your fast and very usefull respons!