How long is a piece of string? Or, how long should my thesis be?

Image “How long is a piece of string?” by Flickr user izzie_whizzie. Used under Creative Commons License.

The first 20-30 pages are a strong indicator of the strength of the candidate.  The abstract and introduction are very important indicators of what is coming next and I read them a couple of times before progressing. usually this is followed in the thesis by a literature review or ‘state of the art chapter’. Get this right and then write a good method chapter and most examiners are confident and relax into the examination of the thesis.

How many chapters?
Elsewhere I’ve talked about applying one of the principles of flower arranging (using odd numbers of blooms) to the number of studies to include in PhD research. The computer science supervisor, Christopher Clack thinks this applies to the number of chapters in a thesis and recommends, “An odd number of chapters, between 5 and 9.”

How many pages? 100-300 pages of double space single-sided text
First, check your university guidelines. If they do not specify a length then assume 100-300 pages and check with your supervisor(s)/committee. In my experience the 100-300 pages holds true but it is also backed up by anecdotal evidence from other examiners and supervisors. There’s also some more data-driven evidence for the 100-300 pages. That is double spaced and single sided pages with a one inch margin all around and 12 point Times font.

All of us who examine PhDs have probably hefted the weight of an especially heavy thesis and groaned. It’s not about the ‘thud’ factor.

Pascal: “I would have written a shorter letter but I didn’t have the time”
Clack, writing about non-compilation theses in computer science says, “Average, good, size for a thesis is 150 pages all in. Perhaps up to 50 extra pages for a big appendix and bibliography. Beware of the trend to write long and boring doctorates […], improve your communications skills.” In response Steve Wilbur comments, “Over about 100 pages of the body of the thesis I seem to note the strength of the work is inversely proportional to the length. […]. I find 120 pages at usual university layout standards about the limit for good to best theses.”

I sometimes read theses of 350 pages but that is really only acceptable when a LOT of images and diagrams are incorporated. An over long thesis often indicates an lack of focus which in turn makes the contribution to knowledge harder to identify. Good writing is about precision.