A key element in the successful completion of doctoral programs is the preparation and defense of a research project – dissertation (Doctoral thesis). The thesis represents the independent research work of a graduate student, in close cooperation with the supervisor.
Programs and departments set their own requirements for the scope of the dissertation project in the Humanities and social Sciences, typically 80,000-100,000 words, and in the sphere of the exact Sciences – 40,000-50,000 words.
The tentative structure of the thesis looks like this:
In the UK, the thesis is called a viva voce, i.e. an oral examination (from the Latin for "live voice"). On defense, there are two or more examiners and the candidate. One of the examiners is representative of the University the candidate (but not his supervisor), the rest of the examiners is external, from other universities. The presence of the principal scientific adviser to the defence is not required, and he has no right to ask questions during the exam.
In most universities such protection are held behind closed doors, however, some universities, e.g. Oxford, authorize the presence of University members for doctoral dissertations for the degree of DPhil.