How do i generate 1000 patients from 8AM to 6PM following a distribution?

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question

Lenny C asked Sep 22, '21 Matthew Gillespie commented Sep 27, '21

How do i generate 1000 patients from 8AM to 6PM following a distribution?

Hi,

Assuming i know the distribution of patient arrival, is it possible to create these patients (eg 1000 patients) with interarrival rate following the distribution throughout the day from 8 AM to 6 PM?

Understand that i can set the number of patients arriving at different time of the day using Date Time source that is evenly spaced / randomly spaced / scheduled time. Is it possible to set it to a distribution instead, without generating the table outside of Flexsim (i.e using excel)?

For example using Date Time Source and changing the "Randomly spaced" to follow a distribution instead.

Thank you!

Software Version:

FlexSim 20.1.3

source schedule distribution interarrival times

1632273318480.png (43.9 KiB)

· 4

David Chan commented · Sep 22, 2021 at 02:36 AM

@Lenny C This is the exact solution to your question

David

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Lenny C David Chan commented · Sep 24, 2021 at 06:37 AM

Hi David,

was wondering if it is possible to not use Randomly Spaced and instead, change it to a distribution (eg poisson distribution)

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Joerg Vogel Lenny C commented · Sep 24, 2021 at 07:03 AM

Sure, but what would you gain. Your conditions set boundaries, which works against a distribution. You have a time limit. You have an event limit. A method would be to draw 1000 events of a distribution without any boundaries. Then you normalize the occurred events against your time interval. The result is, you have a sequence of events following a draw from a distribution. But if you test this draw against the deviation to the distribution, you might be disappointed, because the deviation is larger than expected and the draw fits better to another statistical distribution. The accuracy depends mostly on number of events and 1000 events are small against infinity.

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Ryan Clark commented · Sep 23, 2021 at 08:54 PM

Hi @Lenny C, was David Chan's answer helpful? If so, please click the "Accept" button at the bottom of their answer. Or if you still have questions, add a comment and we'll continue the conversation.

If we haven't heard back from you within 3 business days we'll auto-accept an answer, but you can always unaccept and comment back to reopen your question.

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Answer 1 · 2021-09-24T14:47:35Z

Matthew Gillespie answered Sep 24, '21 Matthew Gillespie commented Sep 27, '21

@Lenny C What is your distribution?

If it's the number of time units after 8 AM that the patient shows up you could enter that into the Offset / Variability field.

If it's an inter-arrival time you can create a token at 8 AM that then goes through a loop of 2 steps until 6 PM:

Delay for the inter-arrival time
Create patient

· 3

Lenny C commented · Sep 27, 2021 at 04:11 AM

Thank you!

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Lenny C commented · Sep 27, 2021 at 04:15 AM

If i have 1000 patients entering with interarrival rate following a distribution (1 after another), may i know how i can do so?

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Matthew Gillespie ♦♦ Lenny C commented · Sep 27, 2021 at 04:35 PM

The attached model creates 1000 patients with an inter-arrival time distribution spacing them out.

1000Patients.fsm

It just has a token looping around and waiting the inter-arrival time and then creating the patient. After doing this 1000 times it goes to a sink.

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1632760517626.png (13.0 KiB)

1000patients.fsm (43.2 KiB)

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