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Rafael de Assis avatar image
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Rafael de Assis asked Rafael de Assis commented

How to adjust the distribution in Expertfit?

Hello Everyone!

I'm young to FlexSim, and I need your help!

My model simulates a painting station. I have a question because in my "source", I used Expertfit to find the best distribution.

I took 104 observations in my sample. These observations are in quantity per hour.

When I plot the result indicated by Expertfit, I'm far away from my current situation. I had the expectation of 4 flowitems per hour, but my result is far from this goal.

I don't know if I might be committing some mistake in the treatment of the data.

In attached is the data and my 3D Model. The Expertfit model is inside the link below.

Modelo avançado V21.fsmDados para expertfit.xlsx

https://www.dropbox.com/scl/fo/qg6319ap0n1romb3aus9k/h?rlkey=qkvhq2dz56n2x1c644xh7qrvy

Thank you

FlexSim 21.1.5
expertfitdistribuition
modelo-avancado-v21.fsm (148.8 KiB)
dados-para-expertfit.xlsx (17.5 KiB)
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Joerg Vogel avatar image Joerg Vogel commented ·
@Rafael de Assis, if you have 104 statistical distributed events you can still go with an empirical distribution. You must find from your empirical data a mechanism to compute a Delta from one event to another and the to get a next interarrival time.
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Natalie White avatar image Natalie White commented ·

Hi @Rafael de Assis, was one of Felix Möhlmann's or Lucas Matheus's answers helpful? If so, please click the "Accept" button at the bottom of the one that best answers your question. 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 comment back to reopen your question.

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2 Answers

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Felix Möhlmann avatar image
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Felix Möhlmann answered Rafael de Assis commented

It looks like the distribution you use in the source is modelling the number of arrivals per hour. The inter-arrival time should be the reciprocal value of this (to get 4 items per hour, the time between two arrivals must average 15min).

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Rafael de Assis avatar image Rafael de Assis commented ·
Thank you so much! I got it!!
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Lucas Matheus avatar image
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Lucas Matheus answered

The distribution is wrong due to the data collection format. To use source in this format (inter-arrival), you need to collect data on an event-by-event basis, not an hourly rate.

As stated by @Felix Möhlmann, the average of your data should be approximately 15 minutes (therefore, a unit of time and not a rate).

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