Modelling

One of the objectives of NZCEE is to develop models that can be used to test "WHAT IF?" situations to help anticipate the environmental and economic outcomes of different policy options.

There are a number of different approaches to the development of mathematical models. A modeller's choice of method is usually determined by factors like the size of the problem being modelled, and/or its level of complexity and the state of current knowledge. The state of current knowledge is a critical factor.

Theoretical models are usually constructed by using a systems perspective. In this type of approach we first attempt to identify things like:

• the boundaries of some natural phenomena
• their internal elements, and
• their interrelationships

The construction of a mathematical model that adequately portrays the level of complexity needed for this project requires the use of modelling tools that are easy to use, flexible, and yet capable of handling emergent scale and complexity.

'Stella' has been choosen as the modelling tool as it fulfils/answers all these requirements. Stella's various object tools can be arranged to produce a diagramatic model. Each object shown in the Stella diagram has a deeper mathematical meaning. The Stella script file associated with the diagram contains the data, equations, variables and parameters.

Further detail about the modelling approach used can be found in the Modelling Software & Approach.