Population, Natural Resources and Food Security Lessons from Comparing Full and Reduced Form Models

This paper discusses one of the most difficult issues in modeling complex population-environment interactions: The advantages and disadvantages of highly disaggregated empirical models versus highly reduced theoretical models. The analysis is carried out on the basis of the PEDA model, recently developed to capture interactions between population change, education, agricultural production, food security and natural resource degradation in Africa. An important feature of the approach is a non-linear food distribution function. Ranging in its use from direct science-policy communication with a number of African governments, to highly advanced dynamic mathematical analysis, PEDA turns out to be appropriate for the kind of sensitivity analysis and comparison of different levels of complexity attempted in this paper. In short, the results show that highly reduced models can never replace full empirical models, but that they show important additional features that complement the full models. For the researcher, the best understanding will be gained if one does not limit ones analysis to one level of complexity, but compares results from different levels.