Gary's research interests are primarily focused on methodological aspects surrounding the development and validation multivariable prediction (prognostic) models (design and analysis) and he has published extensively in this area. He is particularly interested in the sample size considerations and the role of big data in developing and evaluating prediction models. He is also interested in the systematic review and appraisal of prognostic studies and developed the CHARMS Checklist for conducting systematic reviews of prediction modelling studies. Gary is the principal investigator of a five-year Cancer Research UK Programme grant (2019 to 2024) to improve statistical methodology around studies of prognosis (with a focus on machine learning and artificial intelligence) and initiatives to improve peer review and study reporting.