Simplifying general equilibrium analysis through a modular structure: MAGNET

This paper discusses some philosophy behind the MAGNET modelling system. One basic idea is that the model code and the code to manipulate data is split in more or less independent components. A second basic idea is that the manipulation of data and scenarios should be coded completely. A system called DSS has been developed to guide data manipulations, model aggregation and simulations in a systematic way, and to store all choices for model code used, data used and shocks given in the simulations in a standard manner. This enables to reuse procedures that have been developed and to reproduce principles of simulation when the GTAP database or other databases change, or when the regional or commodity aggregation changes. A system called GEMSE_Analist helps in interaction with the DSS system to analyse scenario results in a systematic manner. An interface for coding called GTREE allows also for reusing the same code with different sets, parameters or variables at different places as a type of subroutine. Finally, the structuring of code through GTREE helps to make the code more intuitive if the philosophy of intuitive coding is followed. In summary, a number of important issues that are relevant to work with the modular approach of MAGNET are discussed.