What is the size/scope/style/length of PhD dissertations in your field? Do they have a lot of background material or focus on the student’s original contributions? Are they comprehensive (everything the student has done, even if fairly disjointed) or a coherent body of work?
A typical dissertation in my group is between 100 and 150 pages, with most 120-130, and this appears to be pretty common in my department. I like to keep them very lean, focusing only on what the student has done and published as first author or as the lead theory student within a collaboration with experimentalists; basically, a dissertation is very close to papers “stapled” together. There is a common introduction and a common conclusion/outlook, but the actual chapters inside are the students’ original work. If a student has published well, writing the dissertation should be quick and painless IMHO.
Also, I like the dissertation to be coherent, i.e., basically the largest interconnected body of work that the student has done and that can be placed under a common umbrella. On occasion, I have a very productive student who has taken part in several very different projects and published well on all; in that case, we pick the project of which they feel the most ownership as the one to write the dissertation on, and while the satellite work doesn’t make it into the dissertation, the student definitely mentions it in the defense and even very briefly discusses the highlights before diving into the dissertation project.
Why do I ask?
A colleague from another department who will be on one of my student’s dissertation committee came to ask what the norms in my department were in terms of dissertation length. If it were me, I would have left it at that and waited to hear what the norms were, but the colleague had to add “because this wouldn’t pass muster in my department.” (Do dudes ever get told condescending stuff like that, seriously?) I got very ticked off, because this is one of my best and most versatile students, and is worth a PhD twice over. His dissertation work was extremely complicated and he did a great job, which he published in several papers, and then wrote up for his dissertation. He also did work on three completely different side projects, all with papers published, which did not make it into the dissertation.
The implication of “not passing muster” based on document length was really irritating. So I went and looked at some of the colleague’s group dissertations, and they were in the 300-400 page range. Maybe it’s the colleague’s subfield norms (e.g., dump all from lab notebook in dissertation) or there is a lot of filler text (since we are being condescending here), because I have been on committees for other folks in the colleague’s department and the dissertations look about the same as in mine.
So what say you, blogosphere? What is the size/scope/length of PhD dissertations in your field? Do they have a lot of background material or focus on the student’s original contributions? Are they comprehensive (everything the student has done, even if fairly disjointed) or a coherent body of work? (Please state your field.)