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Joflexsimwo avatar image
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Joflexsimwo asked Jason Lightfoot commented

How to have random streams across different scenarios and replications?

I am running experimenter. I have 3 scenarios and ran 30 replications each.


Currently, the process timing for Scenario A, B, C for the Replication X is the same.


What can I do so that all 3 possibilities:

1. Scenario A, Replication X

2. Scenario B, Replication X

3. Scenario C, Replication X

are all different?

FlexSim 22.2.0
experimenterexperimentorexperiment and seed
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1 Answer

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Jason Lightfoot answered Jason Lightfoot commented

The streams for replication X are the same - this is by design and is a recognised variance reduction technique. It allows any differences in the scenarios to be driven primarily by the difference in the scenario and not some arbitrary random variation.


The random differences that you should be looking for - the alternate universe where events play out differently - are handled between the replications X and Y - not the scenarios.

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Joflexsimwo avatar image Joflexsimwo commented ·

Hi @Jason Lightfoot

I have a list of labels stored in a list, whereby it is randomly selected by SQL query and assigned to flowitems.


Why does this happen?


Across the replications X, occasionally, different scenarios have different labels.

For example,

1. Scenario A, Replication X, Flowitem 1 is labelled as A1

2. Scenario B, Replication X, Flowitem 1 is labelled as B2

3. Scenario C, Replication X, Flowitem 1 is labelled as A1


Most of the time, different scenarios have same labels, across the replications X.

For example,

1. Scenario A, Replication X, Flowitem 1 is labelled as A1

2. Scenario B, Replication X, Flowitem 1 is labelled as A1

3. Scenario C, Replication X, Flowitem 1 is labelled as A1


Thanks!

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Jason Lightfoot avatar image Jason Lightfoot ♦♦ Joflexsimwo commented ·

Are you testing this in the experimenter or by setting the scenario and stream manually? Do you have Repeat Streams selected in the Statistics menu?

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Joflexsimwo avatar image Joflexsimwo Jason Lightfoot ♦♦ commented ·

@Jason Lightfoot

Yes, I am testing this in the experimenter. I did not set the stream manually. I do not have repeat streams selected in the Statistics menu.

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