I have just finished my master degree (TU Vienna) and I am working 20 hours per week. I have talked to several professors in my field of interest and they said that the earliest position for a PhD would be in December, because of funding.

However, I think I could take the route as external researcher and do my PhD by working 20 hours per week and devoting the other 20 hours to my research.

By browsing some posts here I have read that a lot of you consider an external PhD as inefficient (it takes a long time, etc.). Why? What are the reasons for that? Can't such a PhD be done within 3 years?


PS.: What are mostly the reason that it takes so long?

  • 6
    If a PhD usually takes 3 years and you only work half time on it, how could you expect to finish in 3 years? Commented Jun 22, 2014 at 16:08
  • 22
    Assume that a regular PhD student works 50 hours or more and takes 3-5 years. You will realistically work 20 hours or less, have more distractions, and your environment will be much worse. You can do the math.
    – xLeitix
    Commented Jun 22, 2014 at 16:10
  • 3
    @ChrisWhite Thankfully, this has not been the case in any of the groups where I worked so far.
    – xLeitix
    Commented Jun 22, 2014 at 17:48
  • 11
    @ChrisWhite I don't see how this should be field-dependent, and your link describes one old letter that doesn't prove anything. I'm an astronomer, but I'm also a human. No way will (or can) I work that hard for a sustained period of time.
    – Moriarty
    Commented Jun 22, 2014 at 18:03
  • 2
    While I've known people who were "on the job" 80+ hours a week in nuclear and particle physics (and I've had hell weeks up around 100 hours when things were coming to a head), I don't believe I've known anyone who could be steadily productive at that level. The people in my field I look at and say "I wish I was that good." seem to do 50-60 hours of good work every week plus show up to some meetings where they don't have to contribute much. It's not how long they work, it's how much they get done in each hour. Commented Jun 22, 2014 at 21:43

3 Answers 3


This advice is based on Computer Science mostly, and it may or may not apply directly to you. As far as I understand your area is only marginally related to Computer Science through the fact that you're interested in Algorithmic Trading.

Everything depends on two factors: your goals and the speed with which you are able to learn and create the things that you need to do in order to achieve your goals. If your goal is to be a professor at TU Vienna, then you will obviously at some point need to submit a PhD thesis and later a Habilitation thesis. The PhD thesis can have 3 to 6 papers in good conferences and one - two papers in some journals, and your habilitation thesis will consist of a minimum of 5 articles in good journals (A-level journals). You will also have to submit some grant proposals and after you manage to get those grants to finish them successfully (typically the requirement is to have EU grants or ERC grants). So you will have to produce at least 15 conference articles, 8-10 journal articles, 2 thesis, and 2 grants in order to get to an Assistant Professor or Professor in Vienna. If you manage to get every paper accepted first time when you submit it (something unheard of), you will still need 6 - 15 years to get to Assistant Professorship or Professorships (counting from the first year of your PhD). Keep in mind that at TU, Assistant or Junior Professorships appear only once at two years or so (and just one position). Most of the people I know from Vienna (TU Vienna, WU, IST Austria, etc) were able to finish PhD thesis in 4-5 years (full time) or 7-8 years (part-time), so there is no reason to consider that it might take a decade.

The system also makes you quit really fast (after 1-2 years) if you do not want (or you are not able for some reason) to put in the effort that is required in order to create at least a decent thesis. The professor will stop talking to you if you don't make any progress for a number of months, for example, or if your papers are not accepted at top conferences. What you need to understand is that your supervisor is your guide, but you will eventually make the journey alone. The supervisor will just help you polish your articles or thesis.

These being said, before applying for a PhD, I would check the CVs, thesis and articles written by TU Professors (Thomas Eiter, Georg Gottlob, Radu Grosu, Silvia Micksh, Stefan Woltran, etc). It helps a lot, as their expectations are that you will produce some work that is at least partially connected to their last articles (so that your work will also fit into their various research projects). Also try to talk with some of their students (you can easily detect them by looking through their CVs - they might have a PhD students entry - or through DBLP or Scholar by looking at their latest publications and identifying collaborators that only published few papers in the last 2-3 years). Try to understand what a PhD means, what are the expectations, and what is the amount of work you need to put in order to get to good results.

I would also recommend you to check these interesting slides from one of the professors I just mentioned: http://www.ifs.tuwien.ac.at/~silvia/research-tips/.

The idea is to try to estimate the expectations, the amount of work needed and the time you think you will need in order to fulfill this work. The actual number of papers depends a lot on the domain in which you are working, but also on the quality of the outlets where you will publish (you might end up with a smaller number of papers if all of them are only in the top outlets for your field). Good luck!

Disclaimer: I do not directly work with any of the persons already mentioned, but I do work at a university from Vienna.

  • 1
    "If your goal is to be a professor at TU Vienna..." Where did this assumption come from? The OP said only that he had a master's degree from that university and is interested in doing a PhD there (and, perhaps, elsewhere). I didn't see that the OP said anything about her post-PhD plans. The explanation that follows also contains many unstated assumptions about the academic field (which, so far as I can see, was not specified).... Commented Jun 23, 2014 at 0:18
  • 1
    ....You give very specific information about numbers of papers and so forth. In mathematics, for instance, these numbers are certainly inaccurate: I took the time to check that the Head of the Geometric Analysis Research Unit at TU Vienna has 16 publications now: when he was hired as an assistant professor, he had 7-9. Why you list five out of presumably hundreds of faculty there is also confusing. In summary: your answer is highly specific in a way which is not clearly pertinent for the OP. Someone who does not know which information to discard for their situation could be misled. Commented Jun 23, 2014 at 0:23
  • 1
    A little more searching seems to indicate that the advice you are giving is concentrated on computer science, whereas the OP's master's degree is in quantitative finance. It would be very helpful if you could explicitly indicate the range of applicability of your answer and address whether or not it applies to the OP. Commented Jun 23, 2014 at 0:37
  • @PeteL.Clark Thanks! That is true. My advice is related to Computer Science because that's my field. It is also true that the number of papers depends on the field, and also on the requests of your supervisors and of the guidelines of the faculty. I will modify my answer to clearly state that this is the situation from Computer Science.
    – paxRoman
    Commented Jun 23, 2014 at 9:49
  • 1
    Dear @Kare - here is the second part of the answer: You can also launch a company if you are a good researcher. There are grants for up to 2 million EUR for starting a lab, and an additional 200k for starting a company that sells the product of that lab. If you think about it, academia is just another type of business: one that is a bit more abstract, but ultimately our goals are money, vacations, less stress while doing what we love. These being said being successful in the industry will always get you more money, more rewards, but you will certainly be busier...
    – paxRoman
    Commented Jul 19, 2014 at 12:20

Being a PhD student is a full-time job.

True, "officially" you may be assigned to 20 hours of "study" and 20 hours of "work" by the university, but this is just a way to determine your salary, and does NOT reflect the amount of time you actually spend on research studies.

In the U.S., the nominal time for PhD is about five to six years average. This assumes the student is a full time student. While some people finish their PhD in three years or less, this is truly exceptional. The average is six. (This was the case at least in the school I attended, in the Computer Science department. Length may vary in other departments.) It also depends on what you aim for in your PhD: is graduating after publishing just one paper good enough for you?

Now let's do the math. If it takes about six years to finish a degree, assuming full time, then how much time would it take for a part-time student? Take into consideration also 20%-30% extension of time due to context-switching, but also reduce 15%-25% of the time due to being more efficient (it's easier to waste time when working full-time, in my opinion).

You arrive at 10+ years.

Then again, I know people that worked part-time and studied part-time, and were able to complete their PhD studies in four to six years. I also know people that took five to six years to finish their MSc degree (which nominally takes two years), due to having another full-time job.. It depends mostly on your abilities and aims from PHD (but also quite a bit on your luck).

  • Thx for your answer! What do you mean by "luck"?
    – Carol.Kar
    Commented Jun 22, 2014 at 17:04
  • 13
    luck in choosing the right research question; luck in choosing the right advisor; luck in discovering new (awesome) things; luck in getting a work accepted to publish; etc.
    – Ran G.
    Commented Jun 22, 2014 at 17:42
  • 6
    @Kare and luck as in not having any monumental setbacks.
    – Moriarty
    Commented Jun 22, 2014 at 18:06
  • 6
    Luck is setting out ocean bottom seismometers and them having all their data when you pick them up 5 months later: research is a scary and fickle business.
    – Neo
    Commented Jun 22, 2014 at 19:21
  • luck = randomness. I just point this out because for some people, "luck" is a systematic bias in favor of a person -- a supernatural force. These people may think that you are crazy if you indicate that you believe in "luck". In the context of a PhD, randomness is a big factor because you are doing something that has never been done before, which makes your work inherently unpredictable. Furthermore, you are judged largely on your output -- there is not much credit for effort. Finally, the workplace is less organized than for other work -- therefore, more randomness.
    – adam.r
    Commented Jun 23, 2014 at 6:13

And to add to what Ran G said, if you work at half the speed, it will take you longer to produce scientific results, duplicating the chances that you get scooped.

This said, it is common for medical doctors and some nurses with a full time job to do a PhD, but that is a whole different beast (and does take many years).

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .