Hints for PhD Defenses
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
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 limited time.
- 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.
- 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 them.
- Number your slides, particularly if one of your committee members is
linked in via speakerphone. Consider using some kind of remote
- 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"
- 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
- 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 the presentation.
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 engineering degree...
- You are likely only to defend a PhD thesis only once; your defense
is a special occasion, so consider dressing appropriately, at least
business casual, but a suit is not inappropriate.
- It is customary to provide refreshments for the audience, such as
coffee, bagels, cookies and fruit, depending on the time of day.
The Role of PhD Committee Members
- Committee members (should) read the draft thesis (and provide feedback). Obviously, students
appreciate an in-depth reading, but it is common for committee members
to focus on chapters closest to their expertise. Reading depths varies -
some provide line edits, others just suggest larger issues that should
be addressed ("Your related work section in Chapter 10 is a bit sparse
and ends in 2005."). While this is probably not the place to suggest "do
another year of research", filling in gaps is ok and I'd rather postpone
a defense by a month if needed. Before the committee gets the thesis,
I've done a first or sometimes second reading, but the whole point of
the committee is to keep the advisor honest (and complement his or her
knowledge or taste).
- Committee members attend the PhD defense, usually in person.
Typically, this lasts about 90 minutes. Take notes on any editorial
improvements (e.g., "make clear that the throughput graph is measured in
gallons/minute"). Vote on the outcome and sign the form.
- If the student is given a set of changes to implement, the advisor
asks students to detail on how they implemented the changes, similar to
how an author may respond to reviewer comments for a journal. The
committee informally signs off, or not, on these changes. There is no
need to re-read the thesis.
Checklist for Dissertation
Before you submit your draft to the committee, be sure to verify
that you have done the following checks:
- 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.
(Contributions by Ed Coffman, Jonathan Rosenberg and Sal Stolfo.)
[Hints for PhD proposal
defenses] [Writing style]
"So long, and thanks
for the Ph.D.!"
to be a programmer
by Henning Schulzrinne