Which is more important for PhD applicants — Quality or quantity of research papers?

Question

While applying to a PhD program in computer science, which one is more important?

Publishing 4 or 5 medium/low-quality journal or conference papers or publishing only one paper in a top journal?

The review process of top-quality journals are usually 1-2 years. Which means, one has to begin his/her research during the bachelor's and submit the paper in the beginning of master's degree. But as far as I know, this is extraordinary (especially in my country).

An extra question would be: Regardless of the quality of the paper, is publishing papers in distinct areas or publishing papres in a specific area more important?

I'm willing to move to Northern Europe (UH, TUT, KTH, KU). So, answers from the professors/students of those universities will be highly appreciated.

Answer 1

I disagree with the assumption that top journals with slow turnaround times are more highly regarded than top conferences with quicker turnaround times. In most (all?) areas of computer science, the most competitive conferences are at least as highly regarded as the top journals. It is also not unusual for longer versions of conference papers to later be submitted to journals.

As David Patterson (UC Berkeley), Larry Snyder (University of Washington), and Jeffrey Ullman wrote in Evaluating Computer Scientists and Engineers For Promotion and Tenure:

The evaluation of computer science and engineering faculty for promotion and tenure has generally followed the dictate "publish or perish," where "publish" has had its standard academic meaning of "publish in archival journals" [Academic Careers, 94]. Relying on journal publications as the sole demonstration of scholarly achievement, especially counting such publications to determine whether they exceed a prescribed threshold, ignores significant evidence of accomplishment in computer science and engineering. For example, conference publication is preferred in the field, and computational artifacts —software, chips, etc. —are a tangible means of conveying ideas and insight. Obligating faculty to be evaluated by this traditional standard handicaps their careers, and indirectly harms the field. This document describes appropriate evidence of academic achievement in computer science and engineering.

Your research advisor should be able to provide you advice more specific to your case.

I agree with amirg that having any publications when applying to a PhD program (especially based on undergraduate research) makes you exceptional. Your advisor's recommendation also counts a lot, especially if he or she is well known.

Answer 2

I will not focus on the conferences vs. journals angle here, as this has been answered by other people and I really think this is not the core of your question. I will assume you meant to ask:

"Publishing 4 or 5 medium/low-quality venues or publishing only one paper in a top venue. What is better for PhD admission?"

Firstly, I am not entirely sure in which timespan you plan to produce all these materials. In my subfield of Computer Science, writing 4-5 B-level conference papers takes most PhD students at least 2 years. Writing 1 top paper requires a very good idea, solid research skills, and typically at least one half-year of full-time research (often significantly more). Doing all of that as a (presumably) inexperienced undergrad or master student besides course work seems very ambitious. From my personal experience, a very good master student will publish 1 or 2 good papers during his master's. That's about the best I have personally seen among my students.

Now, the simple answer to your (implied) above question is that both are likely ok. Both, one top paper or 4-5 reasonable papers, are likely to get you into any of the northern european school in principle. However, note that admission to european schools is often not like in the US (see also here), meaning that it is well possible that you still need to find a professor to take you on, which may depend more on her/his available fundings than your CV.

However, when you said "4 or 5 medium/low-quality" papers, make sure that they are not too low-quality. There is a threshold from which a badly conceived paper can actually hurt your chances in some groups. It is hard to give a hard-and-fast rule here, but in the dark I would avoid any predatory journals as well as any conference that does not appear on any of the international rankings (e.g., CORE). If you have an advisor or mentor from the field, he will be able to help you with selecting reasonable venues.