The motivation for his research is finding practical methodological solutions to challenges in Phase III clinical trials and observational research, principally:
Choosing the appropriate estimand for a trial (i.e. the patient population, the quantity we wish to estimate and how we handle post-randomisation events in the analysis)
Missing data: in particular, practical approaches for exploring and communicating the sensitivity of trial results to a range of appropriate assumptions about the missing outcome data
Statistical methods in meta-analysis
Using routinely collected health care data to inform trial outcome measures.