At Columbia, PhD defenses are generally not public, although CS usually
allows a student audience. Defenses consist of four parts: first, the candidate
introduces themselves, then presents a summary of their work, interrupted and
followed by questions from the committee. Finally, the committee meets in
private to discuss the presentation and dissertation.
While most of the committee will have read most of your thesis, you cannot
assume that everyone has read every chapter.
The committee needs to be able to assess impact and depth. Usually, the
committee has some idea of this before the defense, but whatever the student can
say to make this assessment easier, perhaps just through emphasis, is likely to
make the defense go much more smoothly.
Generally, the whole defense will not take more than two hours, but should
take considerably less time. Part of the challenge of a defense is to convince
the committee that you can summarize the important points of your work in a very
- Your presentation (and thesis) needs to address the following:
- What is the problem you are studying?
- Why is it important?
- What results have you achieved?
- Some committee members will want to know if the works has been published
and where and how it was received. For example, if you have written software,
indicate where it is being used, either for follow-on work or in some
production or test environment.
- Have a list of your thesis-related publications as a slide. Indicate any
awards that a paper may have received. For most people, it's easier to list
some honor than "brag" about it in person.
- If you have presented your work in a conference or at job talks, be sure
to anticipate and address the most common questions asked there.
- It's a nice gesture to provide snacks for the defense (coffee, bagels,
cookies, fruit, etc.).
- The committee should be handed a copy of your slides.
- Be prepared to briefly summarize your background (undergraduate degree,
how long at the university, etc.)
- No more than 30 slides, plus "back up" slides with additional material in
case of questions. The most effective way of making your committee members mad
is to come unprepared with a stack of 80 slides and then madly skip through
- Number your slides, particularly if one of your committee members is
linked in via speakerphone. Consider using some kind of remote presentation
- List your contributions early.
- When presenting your contributions, be sure to use "I" and not "we" so
that the committee will know what aspects of the work where yours, and which
were group projects.
- Keep discussions of related work very brief, but be prepared to answer
questions of the "how does this differ from so-and-so's work" succinctly.
- You will not be asked to prove results again.
- Be prepared to back up any comparative statement with facts, in particular
statements like "works better", "faster", "scalable" or "optimal". If you are
presenting a protocol, how do you know that it works correctly?
- If you have multiple parts in your dissertation, consult with the
committee ahead of time as to whether it makes sense to omit some of them for
Hints for Dissertations
- It is better to focus deeply on a single area then to work on several
topics, each of which is pursued to a moderate depth.
- Systems work must be coupled with implementation and some kind of
numerical comparitive analysis to demonstrate the improvements from existing
or alternate approaches.
- Your thesis needs a one page executive summary that a layperson should be
able to understand. Test: give it to a relative of yours that does not have an
Checklist for DissertationBefore you submit your draft to the
committee, be sure to verify that you have done the following checks:
(Contributions by Ed Coffman, Jonathan Rosenberg and
- Spell check;
- Check for missing chapter or figure references;
- Section, Chapter, Figure are capitalized;
- All references converted from  to [1,2,3];
- Consistent capitalization in captions;
- Verify expansion of all abbreviations at first instance;
- Avoid "tremendous", "huge" and other similar adjectives;
- End to end -> end-to-end;
- Check references for capitalization of abbreviations and missing data such
as page numbers.
PhD proposal defenses] [Writing style]
"So long, and thanks for
How to be a
by Henning Schulzrinne