A major focus of her research is designing innovative intervention trials to improve population health in New Zealand and other countries. She has been involved in a wide range of research and commercial projects working with different organisations and providing statistical advice on study design, data monitoring, statistical analysis and reporting, and expert review. Yannan is a senior statistical consultant of the Statistical Consulting Centre (SCC) since its inception in 2009, and has been a named study investigator and principal statistician in a number of research programmes and projects fully funded by the Health Research Council (HRC) of New Zealand, Ministry of Health and National Heart Foundation. To date she has published over 160 peer reviewed journal articles. She was elected to the membership of International Statistical Institute (ISI) in 2012, an invited statistical reviewer for medical journals, and is a member of the New Zealand Statistical Association (NZSA).