Questions that are better served with a short answer than with a post.
What should I do, if I don’t know a topic?
How many thesis topics get proposed by students, how many by supervisors?
I have no empirical data on this. My personal estimate, however, is that the fraction proposed by students is small, however. Why? Because it is much harder to get a motivated supervisor for a topic that you proposed.
If a PhD-student holds a seminar/lecture/lab-course on X, does that mean that he supervises thesis topics on X?
Not necessarily. Many teaching assignments are done because they need doing, not because they reflect the intrinsic interest of the teacher. However, there is a good likelihood that somebody in the same research group cares about the topic. So if you want to write your thesis on topic X, do talk to PhD-students, post-docs and professors that teach in this area. Even if they are not interested or available themselves, they probably have a colleague who is.
How much ramp-up time should I expect?
The earlier you start, the better. As a supervisor, I have no problem if a student approaches me now for a thesis that should start in half a year. It does get problematic, however, if it should start next week, since I need more time to set it up.
As a rule of thumb, expect a ramp-up of one to two months for internal theses (i.e. the topic is from a university supervisor). Plan at least one month more time for external theses (i.e. with a company). If you plan to write it at a different university, e.g. as an exchange student, start to arrange them at least one term earlier.
Who can I choose as a supervisor?
At TUM, all scientific academic staff can supervise theses. This includees professors, post-docs and PhD-students. Since there are more PhD-students than post-docs, and more post-docs than professors, it is most likely that a PhD-student will supervise your thesis.
While previous supervision experience certainly helps, the most important criterion for good supervision is the time available for it. So rather choose a motivated inexperienced PhD-student that dedicates a lot of time to your thesis, than someone much more famous and experienced that you only get to see when you present the final results.
How should I manage my supervisors if I do my thesis at a company?
If you do your thesis at a company, you have two supervisors: one in the university, one at the company that participates in the thesis. Often you meet the supervisor at the company more frequently. However, the mark gets determined by the university supervisor (typically based on mutual agreement, but in case of conflict, the university supervisor dominates).
The crucial point is to make sure that both are on the same page in terms of their expectations and scope of your thesis. If they are not, you want to find this out (and fix it) early on. This typically works best, if you get them together to discuss their expectations before (or right after) you start. It is much more painful, slow and ineffective, if their discussion happens through you as a proxy.
How many pages should my thesis have?
There is no general answer for this. It depends on the topic and the area of research (a thesis that deals with formal proofs, for example, is often shorter than a thesis that presents the results from a literature survey, even if the same amount of work went into it).
For orientation, ask your supervisor and look at other theses from the same group.
Personally, I do not give page thresholds to my students. I rather read a short thesis that contains all relevant content, than a bloated one (or a document with large fonts and wide line spacing to fill pages 😉
What do I do when I realize, halfway through my thesis, that the entire approach does not work?
Interesting research is not predictable. In many cases, we do not know how well, e.g. an algorithm or a new quality analysis approach will work before we implement and evaluate it. It is thus a necessary part of research to have approaches not meet expectations.
While it is more fun to implement and evaluate an approach that outperforms existing ones, from the point of research, it is equally important to gain knowledge about the other approaches. In other words, if you implement and evaluate an interesting idea, and it turns out to perform poorly, that is not a problem for your thesis. You still created relevant knowledge.
Can I extend the submission deadline for my thesis?
In principle, yes. It requires a formal process, however. If you need to extend, talk to your supervisor as soon as possible. Submission deadlines are hard and the extension often takes weeks to arrange.
However, my personal impression is that most students feel overwhelmed by the work that is still on their plate at some point during their thesis. I know that I did. Some students want to extend even though they had already done more than enough work (but do not realize it, since their own sense of perfection drives them on). In any case, talk to you supervisor. Often reducing the scope of the thesis, or prioritizing the remaining tasks and removing some not needed bonus material are the better solutions than an extension.
Why is this guide not part of the university pages?
My posts are based on my experience and represent my opinions. While they worked well for dozens of students, there are other ways to write a successful thesis. Some supervisors use different approaches, possibly contradicting what I propose here. Since the posts reflect my opinions, and not necessarily those of my university, I felt they belong here.
Furthermore, I want to show you what to expect when you choose me as your thesis supervisor. I always look for students interested in software-analysis, -quality and -maintenance. From back when I searched a topic for my own thesis, I remember how little information I had myself when I decided where (not) to write my thesis. This guide is my attempt at more transparency.
Why is my question not here?
Because I am not yet aware of it. Please ask it to me: firstname.lastname@example.org. (Either in English or in German.)
Some of the answers in the FAQ cover formalities that are determined by the university bureaucracy. They are valid for TU Munich. they probably hold for many other universities, as well. If you are not at TUM, however, please check with your own departments, since there are probably some differences.