# Variation in intial conditions

Syncrosim Forums ST-Sim & State-and-Transition Simulation Models Variation in intial conditions

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• #22193
mhemstrom
Participant

Has anyone noticed that there is variation in year 0 amounts in state classes areas within a stratum? I would expect variation in year 1 of course, but it seems like year 0 should only have the exact value coming in from an initial conditions spreadsheet. Help??

#22194
colin-daniel
Keymaster

Original Question: Has anyone noticed that there is variation in year 0 amounts in state classes areas within a stratum? I would expect variation in year 1 of course, but it seems like year 0 should only have the exact value coming in from an initial conditions spreadsheet. Help??

Non-spatial initial conditions for each cell are sampled randomly from the initial distribution specified. So initial conditions will vary randomly for each Monte Carlo iteration. You can initialize precisely (i.e. without sampling) by specifying a value for each cell using the Spatial Initial Conditions.

#22213
leonardo-frid
Keymaster

One additional note is that under non-spatial initial conditions, if you select “[] Calculate from distribution” and specify the “Relative Amount” values in the Non Spatial Initial Condition “Distribution” datasheet as the number of cells to be used for each record, then the landscape is initialized identically for each Monte Carlo realization. See: https://docs.stsim.net/reference/prop_initial_conditions_non_spatial.html

#22218
mhemstrom
Participant

Thanks to both of you for quick responses. I’ll give your suggestion a try, Leonardo. Do you think it might be worthwhile to put a checkbox in the initial conditions tab or somewhere to allow the user to specify no variation at time 0? Of course, timestep 1 and on would have variation as specified elsewhere.

#22220
leonardo-frid
Keymaster

Thanks Miles, If you apply the checkbox to “[] Calculate from distribution” and specify an integer number of cells for each record, there will be no variation at time 0.

#22221
mhemstrom
Participant

Excellent. Thanks, Leonardo. It would help if I RTFM.

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