Simplified National Models - The Condensed Version of the Food and Agriculture Model System of the International Institute for Applied Systems Analysis

Fischer, G. & Frohberg, K.K. (1980). Simplified National Models - The Condensed Version of the Food and Agriculture Model System of the International Institute for Applied Systems Analysis. IIASA Working Paper. IIASA, Laxenburg, Austria: WP-80-056

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Abstract

The aim of this paper is to give a concise description of the simplified national models as they were developed in the Food and Agriculture Program (FAP) at the International Institute for Applied Systems Analysis (IIASA).

The work on these models was begun in September 1978 and by late summer 1979 the models had reached a preliminary working stage. The reasons for building such a simplified model system are manifold. First of all, it became apparent that the disaggregated and detailed models of all originally selected countries could not be completed by the end of the program. To provide a self-contained product the simplified version was set up at that time. This system is consistent with the detailed one, but works with a more condensed product list (10 commodity aggregates instead of the 19 envisaged for the detailed version), with a smaller set of countries and with substantially simplified supply and demand components. After completion, the more detailed and sophisticated models can be substituted for this simplified version and, therefore, the system will become more and more realistic.

Although we are fully aware of the shortcomings of the simplified version, we hope that it will prove to be a useful demonstration tool. As such, the model will help to make the methodology used more understandable and to stress both its advantages and shortcomings. It also should be possible to indicate what kind of questions the FAP system will be able to answer. And finally, it should enable those modeling groups who complete their work in advance of other teams to link their model with the condensed version and thus test its performance.

The paper is organized in the following way: Chapter 2 contains a description of those countries which are included in the simplified version. In Chapter 3 a brief explanation of the overall structure of the model system is given and the basic requirements for linking the system are outlined. Data sources and aggregation procedures are explained in Chapter 4. Chapter 5 contains a description of the production module used in this system; input levels in agriculture and the allocation model are explained, followed by a discussion of nonagricultural production. Finally, in Chapter 6 some remarks on the exchange module are made, particularly on the Expenditure Share System used for modeling national demand.

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