Ph.D thesis/dissertation defense

Lars Aruns’ threadon passing a thesis defense suggests that the defense was a grueling ordeal. This is not the case with chemistry, as far as I know. In the few departments I’ve experienced, and in talking with postdocs who were schooled elsewhere, the defense is just a formality. You aren’t allowed to defend until your committee has already approved your dissertation. The dissertation consists of all the papers you’ve already published. You pretty much just cut and paste and reformat (spacing, figure size, margins). Write an introduction and you’re done. Some departments don’t even have oral defenses any more (Berkeley, I think). And others will wave them under certain circumstances, such as when the adviser, student, or multiple committee members have moved to other universities. No one wants to waste time to travel for something that doesn’t actually matter.

How does it work in other sciences and in non-science disciplines?

In my program (English lit), it was mostly a formality. I was supposed to submit the final copy of your dissertation to my committee members a month in advance, and of course my advisor had read the whole thing before that, so I knew going into the room that they had read it and had no major problems with it. Basically, the defense was an hour of advice on how to turn it into a book, which chapters could be submitted immediately as articles, etc.

My experience is in Computer Science.

It all depends on the pull of the advisor. E.g., the department chair gets away with pushing thru really crappy students. At one place, the chair managed to produce exactly one student (and that was also his career total). It was a nothing thesis but we all let it go since he needed that on his record. At another place, the committee passed the student but told the chair straight up in the meeting afterwards to never let someone that bad get that far again.

My advisor was quite powerful so I had an easy time considering. It was an interesting experience. Flew into town since I had left ABD. Just showed up at the defense, did a presentation and answered questions. My advisor had a Big Shot (really famous) friend in town who asked some questions. Didn’t need that. The only problem was the outside person* (non-department). Didn’t think much of my writing skills. Yeah, and?

I did attend one defense that did not go well. It was a BS “experimental” thesis. Run a bunch of simulations changing a few parameters and plot the graphs. No thinking required. But one graph had a funny bend in it. The only one like it at all. The room demanded to know what was going on there. The student had no clue. The committee didn’t pass him. Had to recheck and redo some stuff and then defend (that part) again. So that happens.

The worst defense was with one of my students when one of the faculty members didn’t understand the technical use of a term (despite being formally defined) and kept asking questions that it made it seem like there were errors in the research. Which then the outside person wanted to know more about. I kept trying to get the guy to just shut up and drop it to no avail. We agreed to “fix” things in the final submission of the thesis but instead let it stand since there was nothing to fix.

Sometimes the meeting afterwards is pro forma and just a routine check that everyone was okay with things. Sometimes it’s like one of the above cases and blood is nearly drawn.

  • I was the outside person a few times myself. Hard position to be in. You’re the school’s observer to make sure everything’s legit but you don’t want to get involved in a mess. You also don’t want to look like a pushover since then you’d be asked to be on a 100 committees.

It varies a great deal by department, and even by discipline. I did not have a defense, because it was optional in my department. Most people did, even other people who shared my adviser. With them it seemed like more of a formality / rite of passage.

I’m working on my PhD in linguistics, and my department loves defenses. We have two qualifying papers we have to defend, we defend our dissertation proposal, and then, of course, the dissertation. I don’t know how common this is across the discipline; most departments I know of have qualifying exams rather than papers. For the qualifying papers and the proposal, you can get to the defense stage and not pass.

The dissertation defense, on the other hand, tends to be a formality (i.e., you don’t get to that point without the written part being up to snuff), but that doesn’t mean it isn’t going to be hard. It also doesn’t mean you won’t have some more editing to do afterward. I’ve sat in on a couple, and they’re long with a lot of hard hitting questions.

Also, our dissertations cannot just be stuff we’ve done previously, slapped together with a intro and conclusion. You can build off of work you’ve done previously, but there has to be a significant amount of new research done for the dissertation.

Interesting. Since dissertations are technically accessible by anyone, I’m not sure my adviser would have even allowed me to include something that hadn’t already been accepted for publication elsewhere. Just like we’re very careful not to present information at conferences that isn’t going to be published soon.

The ones I’ve seen were more a ritual than an actual defense, mine included. It’s nice to have something more than just a signature to announce that you are done. My defense was to a crowd - if there was a private part I don’t remember it, but my advisor was the top guy in the department and I was his top student.
At Stanford there is a public presentation (with food before) and a private grilling afterwards. I’ve only been to the public part.

I like the idea of just publishing papers, except that most of mine was way too boring for a paper, and most of the papers I published weren’t about my thesis topic anyway. I did manage to publish my literature research chapter, though.

It’s a US/UK thing. I’ve heard it explained elsewhere. In North America, it looks very bad on the advisor if the student isn’t prepared, as they’ve already looked it over and approved it. In my department, the lowest ranking is “Pass with major revisions” and the external would think the advisor was at least as much of an idiot as the student if they wanted to fail the dissertation. In the UK viva, probably because of the much more independent nature of doctoral work, at least in the humanities, there is a real possibility of failure.

Working on a PhD in biology. In my department, defenses are huge. We have both oral and written quals, which can definitely be failed. Public defense is a presentation for which you must be very well-prepared. The profs and grad students love to shoot holes in bad arguments. This is followed by the private defense, which is like Oral Quals, Round 2. They’re not very likely to fail you outright at this late stage, but they have no problem making you do the whole defense again, if necessary.

A few people have responded with mention of “qualifying exams”, although that term has different meanings depending on where you are. I should specify that there are multiple opportunities for Epic Fail in chemistry, just that defense of the final dissertation tends not to be one of them.

Opportunities for FAIL:

[li]Entrance exams[/li]Not sure what happens if you do poorly on these. I didn’t have to take any: “we accepted you, thus we think you know this stuff.”
[li]Classes[/li]1 year of classes. No one fails unless they were an admission error
[li]Joining a lab[/li]I suppose there is a rare possibility that no one wants you. Never heard of this happening. Usually everyone ends up somewhere,
[li]Some sort of literature project[/li]Something else I didn’t do. Often a 2nd-year project where you get a topic approved, make yourself an expert, write a paper, and give a 1-hour talk. People fail this.
[li]Prelim/quals/candidacy exam/etc.[/li]2nd or 3rd year. Defend what you’ve done and your research plan. Write a paper and give an oral presentation (usually to committee only). Passing this officially makes you a Ph.D candidate. Fail and you get a worthless consolation MS.
[li]Independent research proposal[/li]What it sounds like. Write and defend. 2nd 3rd or 4th year. Sometimes people have to redo this, but I don’t know of anyone leaving because of it.
[li]Dissertation[/li]Write and (usually) defend. Everyone wins.

I think most people leave chemistry grad school for reasons other than failing one of the above. My lab had a 25% attrition rate, but most people most people just decided on their own. The boss didn’t kick a single person out. Now, I’m not saying these folks would have done fine if they’d stuck it out. I just think they realized that they were wasting everyone’s (most importantly, their own) time. The only instance I can think of failing part of the list was a coworker who failed the research portion of her prelim (we did research and independent proposal at the same time.) This was a fluke, because she was the best student in the lab in like 5 years. She redid it and went on to get lots of fellowships a very good postdoctoral position.

I think I’ve hijacked my own thread :frowning:

It will vary between countries more than disciplines, as sonnenstrahl says. I do a lot of chemistry thesis vivas in the UK, as internal and external examiner, and they’re a fairly big deal. Failure is rare (particularly if I’m the external - I usually examine in *viva as celebration *mode), but I’ve been the internal with a few arsehole external examiners. I get quite annoyed if we’re examining a talented student with a strong thesis and the external is nitpicking and trying to trip the person up. You can only really fail someone IMO if both weak thesis and weak student are present. Most other combinations should pass.

Worst case was a guy who did a very solid natural product thesis but performed terribly in the viva, and the external was weighing up failing him. I talked him out of it as it would have been outrageous to fail the body of work, but had to re-examine the guy on my own at a later date because the external was so pissed off with the lad’s performance.

I’ve also done one as internal on a really weak student, with a garbage med chem thesis. Her supervisor was canny, though, and picked a pharmacologist as external. They just talked past one another for 2 hours and the external didn’t really clock how bad the student was. I would have had to have failed her if I was external - the experimental section was so bad as to have been irretrievable.

Could those of you who have mentioned it explain the internal/external thing?

The PhD in the UK is examined by two people, not a committee like in most other countries. The internal examiner is from the student’s own dept, and will be a colleague of their advisor. The external examiner is from another university, ideally someone who knows the area of the thesis well.

The external is in charge - they should read the thesis closely and will shape the examination. It’s their job to ask the penetrating questions and get to the bottom of the student’s understanding. Anything is fair game - basic theory, tangential areas, stuff in the introduction that was done by other groups etc. along with the meat of the work done by the student.

The internal will also examine the thesis with a critical eye, but it’s also their job to act as a sort of referee. They should help the student out if they’re flummoxed by maybe re-phrasing the external’s question, drop a few hints etc. They need to moderate the viva if things start going off the rails. If they’ve got a problem with the thesis they’ll say, but it’s poor form if the internal launches into an interrogation on basic theory and mechanism - that would be stepping on the external’s toes besides being ignorant of what their role is in the process.

That’s my experience of chemistry. Likely varies a bit between disciplines.

Perhaps not as much as might be expected - from what I know of music vivas (having not quite got that far myself), your description would pretty much fit.

It depends on the country, the university, and the discipline. I sat on quite a few defenses in math and then spent a couple years as pro-dean, meaning I chaired the defense committee always in a discipline other than math. This is at McGill, and may not be typical even in Canada.

At McGill, all PhD theses are sent to an external examiner and an internal examiner. The latter is usually the advisor. But I had a student once whose thesis I found unacceptable and he insisted, as was his right, on submitting. So I passed as internal and it was failed by both internal and external. But the usual thing in math is that five people gather in a room with a pro-dean, the student, and maybe some observers. Assuming that the internal and external have passed it, often provisionally on making certain changes, we meet and the student presents an outline of his thesis. The advisor will ask a few desultory questions, maybe one other member of the committee pretends to have read it and asks a question, and we vote to accept. The pro-dean invariably expresses his surprise that it ended so quickly and that’s that. Incidentally, if either the internal or external fails the thesis is failed and the student is, in principle, gone. He can petition for a reread of revise and resubmit and these are usually granted but the statutes are quite rigorous.

Now, when I was a pro-dean, it turned out that the members of the committee have read the thesis (you have no idea how hard it is to read a math paper). I had to start by establishing ground rules, like that the total time for questions could not exceed 50 minutes. And that was hard to enforce. The invariable result was to make minor changes that would be certified by the advisor and the revised thesis was accepted without reconvening the committee. I was present as an observer at defense in linguistics that was practically empty. I was the antagonist in the sense that I had read the thesis and found little in it. I wrote to the dean, complaining, and he appointed as pro-dean a very linguistically oriented philosopher, who remarked that he had never seen a thesis so close to failing. But it passed, she was hired besides and the last I heard she was associate dean of Arts.

She effectively replaced a guy who was let go and not only got a job at Princeton, but was founer and head of the cogntive studies group.

I went into my viva (physics, UK) hoping for a grilling. Had I been passed after anything less I’d forever have felt that the bar had been too low for a supposedly prestigious qualification, and it would have been devalued for me.

I got the grilling I wanted - mostly from my internal actually - and both I and my work stood up to the challenge (with minor corrections). I will never again doubt the quality of the work, or whether it was worth doing it, and that was well worth a few hours of tricky questions.

My PhD is in a biological field, and my experience is somewhat different from Ogre’s.

I had a committee of five professors who met several times a year with me. Finally, they decided that I was allowed to defend my thesis. This same group was the group who would decide whether I passed my thesis. They would never let someone take the test if they weren’t going to pass them.

So, the real test came before the public test. Once you’re given a date for the public defense, you’re done.

Computer Science, didn’t go for a PhD. But my master’s thesis defense was a grueling nightmare ordeal. This was in part due to the fact that I defended on the last day of exams for the fall term. I’m convinced that there were professors who were looking to kill the better part of an afternoon, professors I had never seen before let alone met or had classes with. Since my topic was filling in a new methodology for a well tracked area of CS, I got grilled. I had half an hour of talking + fifteen minutes of demonstration followed by an hour and a half of tough questions, that would have continued longer my adviser hadn’t protested. I felt I held my own, but I was glad when it was done.

My thesis defense for my MFA was harsh. After 3 years of painting, I had one day to put up a three room exhibit for a 5 day show. Before I could open the exhibit, I had a 2 hour defense with 5 profs in the gallery.

We spent 95% of the time talking about the ideas and concepts behind the artwork, hardly any time talking about what the art actually looked like.

I passed, but I think about 10% of the students had to come back the next year and try again, with new art.

Months before the defense, I had a thesis proposal meeting that I had to pass, and 3 other long meetings with the 5 profs separately to discuss my artworks progression.

The thing with visual art is that there is no right or wrong answer, and no backing it up with facts. I had to convince and bullshit that my paintings were evidence of what I was trying to relate to “the audience”. I would have much rather done some research and a few experiments and written a paper!

My defense at Oxford was brutal. Two hours of being raked over the coals by the biggest name in the field, and he was the internal examiner. The external examiner was one of the brightest up-and-coming stars of the field. After the defense was over the two told me that he was specifically harsh on me “because you’ve come over from the States and you probably don’t want to come over for a second defense.”

The upside of it was that no job interview or academic conference ever seemed difficult again. The downside was that I realized that academia was probably not for me (though Plan B has worked out pretty well).