Professor Ronald Geskus from our OUCRU unit in Ho Chi Minh City, Vietnam, tells us about the contribution of biostatisticians to complex clinical research. The role of biostatisticians in clinical research is to contribute to trial design, by calculating sample size for example, and to help draw correct conclusions from the data, discriminating important information from noise. They are instrumental in the translation of a practical problem into a statistical model, and the translation of the result into practice.