41. The method of claim 40 , the progressively modifying further comprising adding the given regressor variable to a respective leaf of the model to form the submodel.
41. The method of claim 40 , the progressively modifying further comprising adding the given regressor variable to a respective leaf of the model to form the submodel. 42. The method of claim 41 , the progressively modifying further comprising removing the given regressor variable to a respective leaf of the model to form the submodel.