Andrew's core expertise is in medical statistics, and he has two complementary roles within UCL. Andrew works in the Institute for Global Health, where he is Director of the Centre for Pragmatic Global Health Trials. He is the lead statistician for several ongoing trials in the UK and overseas, many of which are cluster randomised, including parallel group, crossover and stepped wedge designs. Andrew also works at the London Hub for Trials Methodology Research, based in the MRC Clinical Trials Unit. There he pursues a programme of methodological research, which includes methods for cluster randomised trials, and in particular optimising the design of trials with baseline data and stepped wedge trials. He retains an interest in repeated measurements data and missing data, and is looking to develop work on the implications for design and analysis of trials with complex interventions of needing multiple primary outcomes to reflect the range of impact of the intervention.

Andrew has published over 250 peer reviewed articles and is associate editor for the journals Statistics in Medicine and Sexually Transmitted Infections. He also reviews grant applications for funders such as NIHR.