
Modelprojekt, 2. modul, 2004, id:300  
Vejleder:  Per Gregersen 
Findes på RUb:  Ja 
English abstract
In the project a mathematical analysis is made of GTAP  an economic model for quantitative analyses of policy issues on a global basis. The equations of GTAP are presented, together with the economical and mathematical assumptions necessary. A numerical solution to the initial value problem of GTAP is presented. A combined analysis based on the mathematical modelling process, which is described in the beginning of the project. In the analysis it is concluded that the economical and mathematical assumptions and their consequences are hidden from the modeluser. A theoretical validation of the models is therfore impossible. Furthermore, the model assumptions demand that the database is fitted to equilibrium, which together with the models economical assumptions also makes an empirical validation of the model impossible. It is therefore impossible to either theoretically or empirically validate the model, yet it is still used in policy decisionmaking. We ask for a debate on the consequences and uncertainties involved with quantitative use of the model.