Frequently Asked Questions for Defending PHD Students

Follow links from the GSAS Dissertation Office website for formatting details and templates.

It would be wise in most cases to use essentially the GSAS formatting for the earlier version(s) of your dissertation to be distributed to your committee – except perhaps with significantly wider margins and/or greater spacing between lines, for entering comments.  There is no need to print it on heavy paper for committee distribution, regular paper will do – if indeed paper is used at all.  Best to ask each of your committee members in which form he/she would prefer to receive the dissertation for review: some might prefer single-sided, others double-sided. Some may prefer a spiral-bound or 3-ring-binder hardcopy, whereas others might prefer a URL to read online.  It is unlikely that many would like to receive a big pile of loose paper or a huge email attachment.  (In case this isn’t obvious: If your committee member wants paper, then its your responsibility to provide the paper, do not expect a committee member to print it. Remember, these are people you want to be in a really good mood at your defense!)

It depends on whether or not you already distributed your dissertation during a previous semester when you were registered.  You must be registered during the semester in which your dissertation is distributed, although the defense itself may be scheduled to occur during a later semester without registering again. If distribution takes place prior to the first day of the next semester, the previous semester’s registration applies. General information about registration may be found here.

Follow links from the GSAS Dissertation Office website for the latest rules.

No. When the distribution of the dissertation and the defense happens during the summer, you must register for summer session.  (However, you can distribute in the spring and defend in either the summer or the fall without registering again.)

In the case of a student who is supported in an appointed position (usually as a GRA) during the summer, your funding advisor must pay your stipend but the tuition is waived through a special arrangement with the Dean’s office (note this only occurs during the summer, your funding advisor must cover tuition as well as stipend during the fall and spring terms).  There is a special GRA registration during the summer, to avoid the tuition you must register for something called “FULL-TIME SUMM RSRH APPT”. However, the GRA automatically ends (meaning you will no longer be paid) after you deposit the final copy of your dissertation.

In the case of a student who is not supported by a university appointment during the summer, you are required to register for “Matriculation & Facilities” (aka M&F) for the summer session if you will distribute your thesis during the summer.  In almost all cases you (or some external funding source) must pay for M&F yourself; M&F cannot be charged to conventional grants and contracts, and is not reimbursable.

Follow links from the GSAS Dissertation Office website for the latest rules.

Make sure that your advisor(s) agree(s) that you are ready to schedule your defense.

Your advisor must form a defense committee, if this has not already been done, see “Who can be on my defense committee?” below. You then distribute your complete dissertation (not just a sketchy draft) to your entire defense committee at least four weeks prior to the proposed defense date.  Obviously, make sure all of your committee members have agreed to and are available to attend the defense at the tentatively scheduled date and time. It is usually wise to allow a few weeks for the committee to read and comment on the dissertation prior to actually scheduling the defense, rather than scheduling first and then disseminating the dissertation.  You will also need to arrange a room for the defense, ask the Student Services staff how to do this.

Follow links from the GSAS Dissertation Office website for the latest rules.

It is your advisor’s responsibility to form your defense committee, not yours.  However, most advisors will seek your input.

Your defense committee must consist of exactly five (5) members that collectively fulfill the GSAS requirements for defense committees.  Four, six, seven, etc. members are not permitted.

At least three (3) members of the committee (which might be either CS faculty or faculty from other Columbia departments) must be members of the GSAS Faculty. (CS department faculty are not necessarily automatically GSAS faculty, they must be nominated by the Department Chair.  However, it is safe to assume that all tenured or tenure track budgeted CS faculty have already been nominated, or will be nominated when the need arises.)

One of the committee members, normally your advisor, is the “sponsor” of the dissertation; in some cases there may be two “co-sponsors”, such as when you have two co-advisors (or both a research advisor and a departmental advisor).  Another committee member is the “chair” of the defense committee. The committee chair should be tenured faculty. If your advisor is tenured but all your other “inside” members are not tenured, your advisor may serve as the chair of the defense committee and another committee member is nominally designated as your sponsor.

Follow links from the GSAS Dissertation Office website for the latest rules on defense committee formation.

GSAS requires at least three inside members and at least one outside member. There may be four inside members and one outside, or three inside members and two outside.

Normally, three of these members are faculty members holding budgeted or courtesy (dual) appointments of professorial rank in the CS department.  In rare cases, four or five can be CS department faculty – but in that case the others beyond in “inside” three must conduct research far outside your field of specialization to qualify as “outside” members.  GSAS requires that you include a written statement with your defense application explaining how each such outside examiner’s field differs substantially from your field. The remaining members of your defense committee are chosen from other Columbia departments, institutes and centers, from other universities, and/or from industry or government. You need to obtain the CVs of any outside examiners not already holding Columbia appointments for submission to the GSAS Dissertation Office.

Research scientists in CS-affiliated centers or institutes at Columbia, or even employed outside Columbia, are automatically treated as “inside” members if they hold a courtesy or adjunct appointment in the CS department and thus cannot serve as “outside” members.  Enforcement of this rule may be lax.

Follow links from the GSAS Dissertation Office website for the latest rules on defense committee formation.

Ideally, three hours: one hour for the public seminar followed by two hours for the formal examination.  However, two hours or two hours thirty minutes is more common.

Follow links from the GSAS Dissertation Office website for details regarding the formal examination.

You must “apply” to hold your defense, and all five committee members and the date/time/place of your defense must be approved by the GSAS Dissertation Office. GSAS will not approve your application until after it has been informed of the date by which the dissertation was received by all committee members.

To apply for the defense, you should fill out the “Application for Dissertation Defense” form (available here). The top part goes to the dissertation office, and the bottom part goes to the Doctoral Program Administrator in the CS Department. The copy submitted to the department is signed by the department chair and then forwarded to the dissertation office. It is a good idea to check with the Doctoral Program Administrator two or three weeks after the submission that the application has been approved by the dissertation office.

Follow links from the GSAS Dissertation Office website for the latest rules.

Besides the Doctoral Program Administrator, the GSAS Dissertation Office, and your committee, it is customary – but not required – to post a public announcement of your defense seminar a few days in advance. The Doctoral Program Adminstrator will typically post on your behalf.

The department’s PhD students are normally included in the Doctoral Program Administrator‘s announcemnet of the defense.  It is extremely valuable for doctoral students of all levels (including MS/PhD as well as PhD and DES) to witness and learn from the defenses of other students, including but not limited to those fairly “close” to their own research area.  However, be aware that student members of the audience are generally not permitted to ask questions, and must leave at the end of the public seminar portion of the defense.

If you would like to announce your defense to doctoral students (or faculty) in other departments, e.g., EE, IEOR, and/or Biomedical Informatics, you should query members of those departments as to the appropriate mailing lists, since these persons will most likely not be included in the CS department announcement.

GSAS allows for at most one defense committee member to be entirely absent due to “extreme circumstances”, but up to two committee members can participate remotely. If one member cannot participate at all due to extreme circumstances, then only one committee member can participate remotely.   

Follow links from the GSAS Dissertation Office website for the latest rules.

The dissertation defense is a milestone ideally reached with all five
members of a student’s dissertation committee present. When a committee
member can only participate from afar, an accommodation may be made by employing audio or video conferencing during the defense. A maximum of two members of the dissertation defense committee may participate
remotely, but the committee chair and the sponsor must be present at the

The committee chair will register the need for remote participation on
the GSAS Application for the Dissertation Defense
<> , and will
sign the voting sheet on the absent member’s behalf after the defense.
Committee members who must participate remotely are requested to submit comments, questions, and a provisional vote in advance so that the
defense exercise may proceed in the event technical difficulties are
encountered during the proceedings.

[Changes approved by the Executive Committee of the Graduate School of Arts and Sciences on or about January 31, 2012.]

Follow links from the GSAS Dissertation Office website for the latest rules.

The dissertation defense committee may convene when one member is
prevented from participating by extreme circumstances at the time of the
defense. Such a last-minute absence will count toward the total of two
members allowed to participate remotely. If possible, the absent member
should submit before the defense a report containing comments,
questions, and a provisional vote on the dissertation’s approval. The
committee chair will convey these questions to the candidate at the
defense and rule on the quality the responses made. If circumstances
prevent the submission of a report before the defense, the absent
member’s report should be sent as soon as possible after the defense to
the dissertation defense committee chair and to the Dean of the Graduate
School. The committee vote will not be considered final until the report
is reviewed and the defense committee chair determines whether any
further action is warranted.

[Changes approved by the Executive Committee of the Graduate School of Arts and Sciences on or about January 31, 2012.]

Follow links from the GSAS Dissertation Office website for the latest rules.

A packet of forms is supplied by the GSAS Dissertation Office a few days before the defense.  The Doctoral Program Administrator will obtain the packet on your behalf, but it is wise to check a couple of days before the defense that it has been actually  picked up from the GSAS Dissertation Office. You should pick up the “blue folder” from the doctoral program administrator a maximum of 30 minutes before the defense, and bring it with you to the defense.

In the blue folder will be a “Final Examination for PhD voting sheet” that must be signed by your committee at the end of the defense, and then returned to the Doctoral Program Administrator and thence to the GSAS Dissertation Office.  Make a photocopy before returning it! The rest of the packet will consist of information and forms concerned with depositing the dissertation.

Follow links from the GSAS Dissertation Office website for the latest rules regarding defense vote policies.

Your presentation slides, in computer-generated form (e.g., powerpoint on your laptop, printed foils).  Make sure in advance that a compatible LCD or overhead projector will be in the defense room.  In any case, do not plan on using the whiteboard! (There isn’t any rule against it, but you do not want constant “point of clarification” questions during your presentation aimed to decipher your handwriting.)

Your committee will truly appreciate it if you (or your advisor) arrange refreshments, preferably of the healthier variety (fruit, cheese) rather than something that will put your committee to sleep (sugary baked goods). Keep in mind that it is well known that most computer scientists cannot manage for more than 20 minutes without caffeine, although some prefer tea or soda to coffee.

The student presentation part of the formal examination should be limited to no more than fifteen minutes. However, all CS defenses are immediately preceded by a public seminar. The presentation during this seminar should be planned for about 45 minutes, since there will almost certainly be clarification questions asked during it that tend to lengthen this part to an hour (only points of clarification questions are permitted during the seminar).  Then any audience is asked to leave.  Thereafter only the candidate and defense committee may be present during the formal examination.  The candidate may be asked to summarize the pertinent background and findings in no more than fifteen minutes if this material was not thoroughly covered in the public seminar.  Then the questions begin. We do not always strictly adhere to the GSAS formula of 20 minutes per questioner, but it is unlikely that questioning would go on for more than 100 minutes (5 * 20) total.

Follow links from the GSAS Dissertation Office website for the latest rules regarding the formal examination.

The general rule of thumb is 2-3 minutes per slide, not counting the title page (and any “logo” pages or whatever that are only meant to be glanced at). So about 15-22 “content” slides, perhaps up to 30.  However, it would be wise to also prepare numerous “backup” slides with detailed information about your software, your experiments, your results, related work, etc. in anticipation of likely questions.

It is important to understand that there are, in essence, two sessions during which questions might be asked.  The first is during the public seminar, during which questions by the defense committee are limited to “points of clarification”. Extensive questioning must wait until the second session, following the candidate’s presentation, after any audience has left.

However, some defense chairs may optionally allow a short period of general questioning at the end of the public seminar, with the audience still present, prior to the private extensive questioning session.  In that case, if other faculty, research scientists, postdocs or the equivalent happen to be present, as a courtesy the chair of the defense committee may permit or even encourage those persons to ask brief questions.  Other students, family and friends, research staff below the doctoral level, etc. will most likely be strongly discouraged from asking any questions, in the interests of expediency, but of course you should feel free to discuss your dissertation with them privately before the defense or afterwards. Everyone except the candidate and the committee are asked to leave prior to the commencement of the extensive private questioning session.

Follow links from the GSAS Dissertation Office website for the latest rules regarding the formal examination.

GSAS has a strict deadline of six (6) months after the defense.  There are excruciatingly detailed requirements regarding the format. There is also a special card that must be signed by the department chair and the chair of your defense committee, to accompany the deposit.  This card is supplied in your defense packet, but you should be able to get another copy from the GSAS Dissertation Office.

Follow links from the GSAS Dissertation Office website for the latest rules regarding formatting and deposit.

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Last updated August 14, 2020.