The didactic value of linking models: experiences from the LEI model funnel

The complexity of agri-environmental economic issues is such thata model that is fully consistent at all levels of aggregation and alltype of questions to be addressed is not available at the AgriculturalEconomics Research Institute in the Hague LEI. Such a model isprobably also not feasible. At LEI this problem is solved by linkingmodels at different scales of analysis: global economic, nationaleconomy-wide, regional agricultural, national spatial and farm levels.This linked model system enlarges scope and consistency ofthe analysis. The goal of the model linking, however, is not a fullintegration and, ultimately, simultaneous optimization of the models.Therefore, the different models of the LEI model funnel are oftenrather loosely linked. Hence, it is not surprising that the modelssometimes produce different results even for the shared variables.This article describes the difficulties to share and exchange informationbetween different models and identifies possible solutionswhich aim at a more consistent analysis along the models combinedat LEI while maintaining the diversity of modelling approaches.