Improved Methods for building large-scale Bayesian Networks Statement of Interest for the Third Bayesian Modelling Applications Workshop at UAI 2005

Agena Ltd and the RADAR group have been applying Bayesian Networks (BNs) to risk assessment problems in a variety of problem domains for the last five years. Prominent areas in which we have applied BNs include: • Predicting the risk of mid-air collisions between aircraft in UK airspace [17]; • Predicting software defects in complex consumer electronic devices [2,6,8,9]; • Evaluating the reliability and availability characteristics of military systems [15]; • Modelling the warranty return rates of electronic components [3]; • Modelling operational risk in financial institutions and predicting resulting losses. [14] All of these examples involved building large-scale BN models for a real end-user. To support this work we have developed a general BN decision support tool called AgenaRisk [3]. In addition to this we have also developed a number of heuristics that have been successfully deployed and validated in these application areas. We would hesitate to claim these heuristics constitute a methodology, but are confident that they have provided, and will continue to provide, a productive and reproducible means for modelling uncertainty in risk