Each year, thousands of students decide to pursue a PhD. Personally, it took me quite some time to realize that I want to pursue a PhD. However, PhD does not equal PhD — PhD programs or positions vary significantly across countries and institutions. In my case, the decision was considerably easier as I got to know how PhD programs in the United States look, how an industry PhD might work and how the German university system operates. In addition, personal preferences always play a role — in the end, a PhD is a commitment for at least 3 years.
After I decided to pursue a PhD in Germany, it gets complicated: what is actually important for being successful during and after a PhD? The university name, or its rank? The reputation of the advisor — his or her h-index or number of citations? What about co-advisors, the number of publications (and their venues), courses, summer schools and workshops? Or internships? This article is meant as an unordered collection of insights I obtained from reading and speaking to PhD students, post-docs and professors about what really matters.
About "Big" Names and Rankings
As student, one is easily impressed by the renowned universities — those leading most world-wide university rankings. I was no different; when I was presented with the opportunity to have a "big" name on my CV, I was also intrigued to neglect all other factors. Of course it depends on who you speak to — and it would be idiotic to totally neglect the institution or university offering the PhD program. However, I noticed that many good researchers put very little weight on university rankings or the name of the university granting the title. I found it useful to transition from thinking about universities to considering individual research groups. Across the board, one will find good research groups in most disciplines at the top universities. However smaller universities with less reputation may also have excellent research groups in specific disciplines or research areas.
Of course, I am not the only one having problems choosing a PhD program: I found this question on academia.stackexchange very useful.
About Research Groups
When looking at individual research groups it does not get easier. There are many good research groups in all possible disciplines out there — and admission may also be very competitive (as you were not the only one figuring that out). That's where it got really difficult for me — now research counts, that is publications, collaborations, projects, talks, conferences and so on. Here, I quickly got distracted by numbers and rankings, too — Google Scholar profiles, high h-indices and plenty of citations. I am not sure how important these statistics really are. But I remember a talk by Prof. Thomas on my graduation. He talked about rankings in general, but specifically highlighted some interesting facts about the h-index and related statistics. This got me thinking ...
Therefore, I decided to put more weight on the research from the last 1-3 years. Especially from the PhD students — because that is the most relevant to decide. I can only recommend looking at the PhD students in the group, their publications, when they started and when they got their first major publication(s). These may be good indicators that the research group is active — both regarding publications and regarding advising of PhD students. I also considered conference attendance (might be hard to find out), talks and how long it took them to graduate. These considerations really helped me to decide.
About Advisors
The prospective PhD advisor is a completely separate topic and — as I found out — there is no definite checklist for choosing one. In the web, many different experiences and opinions can be found. While these discussions did not solve the problem for me, it helps to sort out important aspects of choosing a good advisor. I found Prof. Ben Zhao's answer most useful:
A great advisor is someone who maximizes the potential of every student he/she works with, as measured by the students' accomplishments, publications, knowledge/experience, and job position at graduation.
So, looking at current and past PhD students and their accomplishments is a good start. However, personal preferences will always play an important role.
I also talked to some PhD students and researchers; some told me that collaborations are always possible — although they might require an active role. In addition, many researchers told me that building a network is important. From that perspective, visiting more than one group and seeking collaborations may be beneficial. For me, however, it will take some years to judge this advice.
About Students, Location and Personal Preferences
Overall, there might be many PhD programs that are suitable and there is probably not the one perfect PhD program. Beyond the aspects discussed so far, there are several additional factors to consider. However, these largely depend on personal preferences and priorities. For example, location might be important — be it family, language or legal restrictions (visas, working permits etc.). Additionally, other factors of the university/institution might be relevant, for example networking opportunities or the alumni network. Similarly, funding (for the PhD program itself) and resources (for hardware, material, conference stays etc.). Finally, the fellow students might be important regarding productivity, motivation as well as social life. Overall, these factors are very individual; more examples can be found here or here.
Some of these more specific points may be hard to judge — except the personal preferences of course. For me, these turned out to play a more important role than I was initially willing to admit ...