PhD students complete an independent research project under the guidance of a supervisory team. The maximum period of registration permitted before thesis submission is 4 years full time / 7 years part time. Active research (including all experimental work, laboratory work, field work, and data collection) will typically take 3 to 3.5 years full time / 6 to 6.5 years part time. On completion of active research students may request approval to register for a writing-up period of up to 12 months. The period of active research and writing-up together must not exceed the maximum registration period. The thesis should not normally exceed 80,000 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.