On completing their research project (typically after 3 years), a PhD candidate must produce and submit a substantial thesis (in science 60,000 to 80,000 words). The thesis is read by at least 2 experts in the field of the thesis topic. The student then undergoes an viva voce examination, when they are questioned by the experts. For the PhD to be awarded, the examiners need to be convinced that the work is novel, of the required standard and that the candidate actually did the work themselves.