Marion Mafham is an associate professor working in the Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU) at Oxford Population Health and co-leads the HDR UK Transforming Data for Trials programme. Her work aims to improve health by generating reliable randomised evidence about the effects of interventions to treat and prevent common causes of death and disability, focusing on diabetes, cardiovascular and kidney diseases. She pioneers new trial methods to design large-scale streamlined randomised trials that produce reliable answers, including the use of healthcare systems data in clinical trials.