Developing Sub-models in Land Change Modeler (LCM)
You can only have 9 transitions in a sub-model. Although this is a hard limitation, when there are more than 9 it can be difficult to say that all transitions can be explained by the exact same drivers of change. To get around this limitation and to develop a more realistic model of historical change, create additional sub-models with similar, but different drivers. Here are the steps to do this.
1. Identify which transitions can be explained by the same drivers. If, for example, you have 3 sets of transitions, you would create 3 sub-model names in the first panel (Transitions Sub-Models: Status) by selecting each of your 18 transitions and assigning them a name in the Sub-Model Name entry box.
In the above example, you may have three transitions to model, deforest, urban, grassland. For each transition pair, enter one of these three sub-model names.
2. In the Transition Sub-model Structure panel, enter the drivers for the sub-model selected. You select the sub-model in the first panel using the drop-down menu for "Sub-model to be Evaluated".
3. After identifying the drivers for the sub-model, create the transition potential map under the Run Transition Sub-Model panel.
4. Go through the process above for each sub-model. Using the above example, you would do this three times for each of your sub-models. Once you have each transitions potential map for each sub-model, then proceed to the prediction.
What this allows you to do is evaluate each sub-model separately. It sounds complicated at first, but in the long run it reduces the complexity of developing a model of change. In the example above with 18 transitions, you need to think through carefully which transitions to group based on determinants of change.
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