By Val Snow
How do those building and using models decide whether a model should be trusted? While my thinking has evolved through modelling to predict the impacts of land use on losses of nutrients to the environment – such models are central to land use policy development – this under-discussed question applies to any model.
In principle, model development is a straightforward series of steps:
• Specification: what will be included in the model is determined conceptually and/or quantitatively by peers, experts and/or stakeholders and the underlying equations are decided
• Coding: the concepts and equations are translated into computer code and the code is tested using appropriate software development processes