The Crops, Livestock and Soils in Smallholder Economic Systems (CLASSES) model
The CLASSES model is the result of a multi-year, interdisciplinary modeling effort to examine feedback relationships between economic and biophysical systems in East Africa. Further information about the project can be found on the project homepage within Cornell's African Food Security and Natural Resources Management Program. This work was supported by the Coupled Natural and Human Systems Program of the Biocomplexity Initiative of the National Science Foundation, through grant BCS – 0215890, with additional support from the USAID BASIS CRSP project on Rural Markets, Natural Capital and Dynamic Poverty Traps in East Africa. The Rockefeller Foundation is providing key financial support for many of the Kenyan doctoral students involved in the project.
The Model and supporting documentation
The following files contain the actual model as well as documentation that provides a model overview as well describing in detail the key components of the economic decision making, livestock and crop and soil submodules. CLASSES is a system dynamics model, built using Vensim software. The model file here is a read-only version that can be easily shared and manipulated to examine model behavior. However, in order to open the model file, prospective users must first download the free model reader program from the Vensim website.
General Instructions
Each individual tab within the model contains variables describing different aspects and components of a smallholder farming system (for example, soil nutrient stocks, cash stocks, income flows, livestock growth rates etc.). Some of these variables can be manipulated by the user to test model behavior under different conditions and scenarios. Within the model there is an 'interface' tab that collects some of the major testing variables (such as land size, household size, initial cash resources etc.) that provides a useful initial starting point for model testing. New users are encouraged to start with the 'interface' tab when conducting initial model runs. Please download the model file and the two additional excel files ('Livestock Data' and 'Nitrogen Application Rate Reference Mode Data') to the same location on your computer. The excel files provide additional data required to run the model.
All questions about the model should be directed to:
Emma Stephens, Assistant Professor of Economics, Pitzer College
emma_stephens'at'pitzer.edu
Model Files