Cathal Walsh is a HRB Research Leader in Health Decision Science. Specific areas in which he has used his expertise are in the modelling of heterogeneity using latent variable models and in combining evidence from multiple sources. He has particular expertise in Meta-Analysis, Network Meta-Analysis and the use of single armed and observational data. He has held visiting appointments in Bayesian groups internationally. He contributes to the statistical societies in the UK and Ireland and served as a member of the Council and theme Director for the Royal Statistical Society. He is a Statistical Editor for the Cochrane Collaboration and has served as Associate Editor for statistics journals. He is an advisor to the National Centre for Pharmacoeconomics on statistical methodology for Health Technology Assessment and on the Scientific Advisory group for HTA for the Health Information and Quality Authority.