What Is a Dissertation Defense?

A dissertation defense is the final oral examination for a doctoral degree, and sometimes for a master's thesis. The candidate presents the research and answers questions from a committee of experts about the work, its methods, results and significance. In the UK and many Commonwealth countries, it is called a viva, from viva voce, meaning by live voice.

How the process works

The format differs by country, institution and field. A typical US defense includes:

1. Preparation: the candidate submits the dissertation to the committee weeks in advance, and schedules the defense.
2. Presentation: a public or semi-public talk, often 30 to 60 minutes, summarizing the research.
3. Questions: the committee, and sometimes the audience, asks questions. Then there may be a closed session in which only the committee questions the candidate.
4. Deliberation: the committee meets privately to decide the outcome.
5. Result: the candidate is told the outcome, and any required revisions.

In the UK, the viva is usually a closed conversation between the candidate and typically one internal and one external examiner, lasting two to three hours or more, and the public presentation is rarer.

The committee

Committees usually include the supervisor and several other academics, at least one of whom may be from outside the department or university. They read the dissertation carefully and test whether the candidate understands the field, can justify choices and can discuss limitations.

Possible outcomes

• Pass with no changes.
• Pass with minor corrections, usually checked by the supervisor.
• Pass with major revisions, which may be re-examined.
• Resubmit and re-examine, in some systems.
• Fail, or a lower degree such as a master's, in rare cases.

Preparing

• Know your work inside out, including the literature, methods, limits and contribution.
• Anticipate questions, such as why you chose a method and what you would do differently.
• Practice a talk and hold a mock defense with colleagues.
• Reread the dissertation, noting weak points.
• Plan logistics, including technology and materials.
• Stay calm. The goal is a scholarly conversation among colleagues.

After the defense

Complete any revisions, submit the final version to the graduate school or library and finish paperwork. The degree is conferred after requirements are met.

Related terms

See ABD, postdoc, external examiner, IRB and gray literature.