Guidelines for good practice in Bayesian network modelling

Bayesian networks (BNs) are increasingly used to model environmental systems, in order to: integrate multiple issues and system components; utilise information from different sources; and handle missing data and uncertainty. For a model to be of value in generating and sharing knowledge or providing decision support, it must be built using good modelling practice. This paper provides such guidelines to developing and evaluating Bayesian network models of environmental systems. The guidelines entail clearly defining the model objectives and scope, and using a conceptual model of the system to form the structure of the BN, which should be parsimonious yet capture all key components and processes. After the states and conditional probabilities of all variables are defined, the BN should be assessed by a suite of quantitative and qualitative forms of model evaluation. All the assumptions, uncertainties, descriptions and reasoning for each node and linkage, data and information sources, and evaluation results must be clearly documented. Following these standards will enable the modelling process and the model itself to be transparent, credible and robust, within its given limitations.