In my PhD studies I have slipped off my original track of research. This was also caused by the fact that I found out that my work can be generalized to a broader scope. It is not so bad, during this detour I did a lot of work.

But then I tried to get back to my original subject and did a lot of work there too. So now after 3 years of studying, I have several papers and a lot of data for both tracks. I don't think that the results in any one of these tracks are sufficient to graduate, but together they are.

Should I:

  1. try to find a unifying theme and try to make my thesis seem unified on the outside, or
  2. should I transparently say that my thesis is about these two subjects?
  • 4
    It could also depend from the rules and customs at your institution (university/school/department). At my department, for example, a PhD thesis is not much more than a collection of articles with an introduction and no unifying theme is even required! Commented Oct 19, 2014 at 21:40
  • It's not very common, but my dissertation had work on two subjects that were only loosely related. (I didn't switch subjects like you, but my interests are broad.) The title ended up being somewhat generic, but it was otherwise OK.
    – jaia
    Commented Oct 20, 2014 at 0:31
  • 5
    I suggest consulting your advisor and PhD committee.
    – Bitwise
    Commented Oct 20, 2014 at 0:46

3 Answers 3


Option 1. At least in computer science, it happens often (but not always) that someone works on several somewhat disjoint but somewhat related problems. It's all about the glue and the story; if you can sell the cohesiveness of the thesis in the abstract and introduction, you're golden. Be upfront about the fact that there may be some disjoint problems, but try to find and highlight the unifying themes.

Here's a quote my advisor always tells us which has relevance to this: "all wells, when dug deep enough, lead to the same water source."

  • Yes, it is computer science :) Commented Oct 20, 2014 at 2:08
  • 2
    Yes, I mentioned in CS because my PhD thesis was in CS and it was REALLY disjoint. It's all about the sell =). That said, my advisor is a really good "salesman". he can take two vaguely related topics and "glue" them well. This is a skill I hope to learn!
    – Tommy
    Commented Oct 20, 2014 at 2:19
  • In social sciences a lot of thesis (and even papers) are about a methodology and one practical application - or about a practical application as a case show of a methodology. This can be a way to glue together different topics if one can be seen as a particular case of the other.
    – Pere
    Commented Oct 20, 2016 at 17:34

This really appears to be about titling your thesis (and maybe writing the introduction). The question, then, I guess, is: who is going the read your thesis and title? Do you want to have a highly descriptive title (Description of topic 1 & description of topic 2), or could you just say (Vague title that sums up both, broadly). In general, I'm not sure if one is objectively better than the other - the audience matters.

  • I think this is a constructive narrowing down of the question, but you finish just saying "I don't know." That's not a good answer in itself. Do you feel the OP's situation is normal and his/her titling is a different and probably less serious problem? If so you can argue that in your answer, even if you don't know how to title it. That would make this a good answer.
    – user18072
    Commented Oct 20, 2014 at 2:41

You should consult with your advisor. Seriously, this should be very obvious to you.

Your advisor is very (solely, perhaps) responsible for the development of your research into a defendable thesis topic. I'm sure that whether this is "usual" highly depends on the idiosyncrasies of your field, but even that's not relevant: from the standpoint of completing your thesis, all that matters is the idiosyncrasies of your advisor with the thesis committee.

I really do hope that your advisor has been signing off on your research to the point of assuring you that these two research tracks together can constitute a defendable thesis, unless I'm misunderstanding and this has been a fairly recent and serendipitous development in your work, in which case "ASAP" would be the best time to introduce this question to your advisor, because you may be wasting time.

Your question may be just about titling or packaging your research - that has been supported by your advisor to the ends of completing your Ph.D. - in which case that's a more docile problem (that I cannot answer). I would recommend posting a new question focusing solely on that or amending this question, if that is the case (IMO new question is better since amending it would change the content of this Q/A thread so much).

  • This is certainly useful advice, but it's not an answer to the question.
    – ff524
    Commented Oct 20, 2014 at 0:59
  • @ff524 1. it's certainly the answer to the questions posed in the body, if not the title; perhaps the question should be amended one direction or the other. 2. solving the underlying problem constitutes a good answer. 3. it's darn near irresponsible to post anything else given that years of this person's career are at stake.
    – user18072
    Commented Oct 20, 2014 at 1:35
  • Use comments, not answers, if you think the question can't be answered in its current state and needs to be modified.
    – ff524
    Commented Oct 20, 2014 at 1:39
  • @ff524 I didn't think it needs to be modified. I thought it was reasonable to solve the underlying problem behind the question rather than permit literal answers to the question title - which would be arbitary to pick over the content - only.
    – user18072
    Commented Oct 20, 2014 at 2:38
  • @ff524 fleshed this out a bit.
    – user18072
    Commented Oct 20, 2014 at 2:53

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