Sensitivity Analysis

The technique of metamodelling and experimental design (Kleijnen, 1987), which has already been applied to IMAGE (Rotmans et al., 1988, Rotmans and Vrieze, 1990, Rotmans et al., 1990), is used to perform sensitivity experiments with IMAGE. In this chapter it is explained how the technique of metamodelling enables us to search for a relationship between input and output variables of IMAGE and how experimental designs can be used to carry out experiments on this model in an efficient and effective way. Various modules of IMAGE have been analysed in this way; the modules concerning the costs of dike raising and the carbon cycle module. First the modules concerning dike raising and the costs of dike raising have been analyzed, because these modules are expected to behave linearly. Afterwards the carbon cycle module was subject to sensitivity analysis, since this is a quintessential constituent of the model. The carbon cycle module is split up into an ocean module and a terrestrial biota module, as described in Chapter 3, and these modules are treated separately. The deforestation module, already integrated in the carbon cycle module now, has not yet been put to the sensitivity test. Moreover it is worth mentioning that an uncertainty analysis has been applied on the modules concerning dike raising and the ocean module of the carbon cycle, with help of the Latin Hypercube Sampling method (Lammerts, 1989).