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Maryam H2 avatar image
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Maryam H2 asked Maryam H2 commented

Poisson process for arrivals

Hi there,

If I use the Poisson process for arrivals with different volumes for AM/PM sessions as shown below (for AM session):

Object current = param(1);
treenode activity = param(2);
int rowNumber = param(3); //The arrival entry row number
int cycle = param(4); //The current cycle through the arrivals table (first iteration cycle = 1)
treenode processFlow = ownerobject(activity);
/***popup:StatisticalDistribution*/
return
/***tag:distribution*//**/poisson/**//**/(/**/
/***tag:par1*//**/33/**/
/***tag:par2*//**//**/
/***tag:par3*//**/, getstream(activity)/**/
/***tag:par4*//**//**/
/***tag:par5*//**//**/
/**/)/**/

I assume that 33 samples will be created and the arrivals depend on the Poisson probability. Is that correct?

And in this case, what would be the effect of using an "evenly spaced" spacing for arrivals?


Thanks!

FlexSim 21.2.4
patient arrivalsarrival patternevenly
5 |100000
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1 Answer

Matthew Gillespie avatar image
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Matthew Gillespie answered Maryam H2 commented

Putting a distribution in the Quantity column of the Date Time Source activity will just give you a variable number of arrivals. So, no, you probably won't get 33 arrivals. You'll get a number generated by the distribution. You'll generally get a number of arrivals around 33, but some replications you'll likely get less than 20 or more than 40:

1636148439317.png

Evenly Spaced will work the same way it would if you just put a number as the quantity. Say poisson(33) returns the number 20 in your model run and your arrival period is an hour, then 20 patients will be created during that hour spaced out every 3 minutes.


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Maryam H2 avatar image Maryam H2 commented ·
Got it, thanks a lot!
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