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Primary transition group settings

Syncrosim Forums ST-Sim & State-and-Transition Simulation Models Primary transition group settings

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  • #3699
    kevinckevinc
    Participant

    When I first attempted to run a spatial model, I received the following error message:

    [Warning] The transition type ‘Competition/Maint’ has more than one primary transition group.
    [Warning] The transition type ‘Insect/Disease’ has more than one primary transition group.
    [Warning] The transition type ‘MixedFire’ has more than one primary transition group.
    [Warning] The transition type ‘NativeGrazing’ has more than one primary transition group.
    [Warning] The transition type ‘Optional1’ has more than one primary transition group.
    [Warning] The transition type ‘Optional2’ has more than one primary transition group.
    [Warning] The transition type ‘ReplacementFire’ has more than one primary transition group.
    [Warning] The transition type ‘SurfaceFire’ has more than one primary transition group.
    [Warning] The transition type ‘Wind/Weather/Stress’ has more than one primary transition group

    I have since been able to eliminate these warning messages by toggling some of the YES/NO settings for each transition type under the Project Definitions tab, but I’m having trouble understanding exactly what this setting means.

    The documentation on the wiki page says, “During a spatially explicit simulation, transition events are created according to primary transition groups. For example, for a primary transition group called All Fire (containing the transition types Replacement Fire, Mixed Fire and Surface Fire) an individual event can be a mosaic of each of the individual types it contains. For spatially explicit simulations it is recommended that each transition type belong to only one primary transition group.”

    It makes sense to me that the primary group All Fire should contain each fire type- I just don’t understand the significance of the YES/NO toggle in the settings and how they should be arranged to achieve this. What about for non-fire disturbance?

    Many thanks for your time and consideration!

    #3701
    leonardo-fridleonardo-frid
    Keymaster

    Hi Kevin,

    This is a good question as it is one of the more complex aspects of the spatial simulation. During a spatial simulation, ST-Sim iterates over each primary transition group to generate “events” for that primary transition group. Events can be a mosaic of transition types within the primary transition group that is being generated, therefore you should only combine types within a primary group that you would expect to be part of the same event. The reason you don’t want to include the same type in more than one primary group is that it will be simulated more than once (i.e., once for each primary group) and thus the input probabilities will not be reflected in the model output. Primary groups could be useful for combining other types of non-fire transitions. For example, you could have different level of severity for insect and disease transitions which could form a mosaic within the same outbreak “event”.

    Regards,
    Leonardo

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