The Department of Population Health Sciences works to understand and improve population health through international quality research and teaching, encompassing determinants of health, interventions in policy and practice, and methodological development. Our research is based around a number of broad themes, with established strengths across epidemiology, medical statistics, public health, primary care, health services research, and psychiatry. PhD students complete an independent research project under the guidance of a supervisory team. The research is normally completed over a maximum period of 3.0-3.5 years (full-time) or 6.0-6.5 years (part-time). A fourth year (full-time) or seventh year (part-time) or the remaining part of this can be used to prepare the thesis for examination. The thesis should not normally exceed 50,000 words and must make an original contribution to knowledge and contain work of publishable quality. The thesis must then be defended in a viva voce (oral) examination before a degree can be awarded.