What is the relationship between impact factor and journal ranking

Question

As a second year graduate student, it's become increasingly difficult for me to figure out what journals are the most prestigious. My research is very interdisciplinary, and so journals from many different fields would be suitable for my work.

Initially, I took Impact Factor as a good proxy for journal ranking. However, I've come to learn that IF doesn't necessarily reflect the whole story. It seems that number of citations (for an individual publication), regardless of journal, appears to be the most important metric.

However, barring that, I assume most people (in the interest of career success), would still like to publish in the best journal they can get in.

Consider a journal like Physical Review Letters. It has an impact factor of 7.7. However, a relatively new journal like Advanced Energy Materials has an impact factor of 14.3, almost double that of PRL. However, I've always heard that PRL is one of the best physics journals that you can publish in (heck, Einstein's EPR experiment was published there). So if I had an article that would be appropriate for submission to both, which would be the better one to get in?

Then there's something like Nature Physics, with its 20.6 Impact Factor, which suggests getting in here would be a more significant achievement that either of the other two. But by how much? Surely not by three times?

(Part of the problem is that Research Gate gives you a total IF score for all your publications, which I think biases that number more than it should be.)

Answer 1

This is a particularly difficult question for interdisciplinary research, because different fields have radically different citation customs and publication time-tables, which leads to the same impact factor meaning very different things. Impact factor also has numerous other problems.

Moreover, absolute ranking of a journal is in many cases less important than reaching the audience that you want to talk to, particularly in interdisciplinary research and especially if you want to reach an application community.

Rather than focusing on impact factor, I would recommend using the following method to determine how to rank journals as possible publication targets:

1. Pick half a dozen researchers who you highly respect and want to be the audience for this paper.
2. Look at the journals that they publish in. The more frequently a journal appears, the better it is as a target for this audience.

This can also help you distinguish between targets for broad and narrow papers. For example, you might have a methodology paper that speaks to a very particular sub-discipline. A journal specifically for that sub-discipline may have a much lower impact factor, but may be a much better place to place the paper and it may actually end up having much higher impact and citations than if it is in a "better" venue where it is mostly read by people for whom it is irrelevant.

Answer 2

If you are interdisciplinary in the sense that you would call yourself a "Theoretical __________", "Quantitative ________", "Computational __________", or an "Applied Mathematician", then if you rank journals by impact factor you will artificially be biased against very good theoretical journals.

As a general rule of thumb (with several exceptions of course) the more theoretical the journal the lower the impact factor. The reason for this is because theoretical work is often more self contained. You cite a book or a few papers for the mathematical techniques or theorems you use, and not much else. Discussions and intros are short, the derivations are the crux of the paper, and the culture is that it is up to the reader to evaluate the importance of the results. It is not uncommon for a math paper to have less than 10 references.

For experimental papers you have to cite a lot of papers just to argue that your results are important. In addition, there are often many similar data sets that your result might shine light on or that contradict or confirm your result. In such cases you'd have to cite them all. Intros and discussions are often long and in many cases are viewed as the most important parts of the paper. It is not uncommon for an experimental biology paper to have 50-100 references.

In my field a good theory journal would have an impact factor above 2 and good applications journal would have an impact factor above 5. You have different audiences reading each. The reason I bring this up is that you mention as your example a general physics journal that accepts a lot of theory papers (i.e. papers with proofs) and one that seems to be more experimentally driven (and as an aside in a very hot field right now). The point is impact factors can be useful in comparing papers within a subfield but are not so good at comparing papers across fields.

If my result is of the form:

• Here is this theoretical result and it explains data from experiments or what we observe in the real world...
• Here is this theoretical result and it shows that all these experiments people are doing are missing the point. We should be doing these experiments instead...
• Here is this theoretical result and it means this for how we should be building ...

Then I want to publish in the applications or general science journal to reach a wider non-theoretical audience because the whole point of the result is its implications

If my result is of the form:

• We built this mathematical model which can be used to describe real world system; it has some really interesting behavior, but its unclear if this behavior is relevant to the system the model can be used to study
• We studied a mathematical model and proved X Y and Z. People have been using this model for a while and numerically have showed that it does a "good job" at ... we prove it actually does do a good job at ....

Then I would publish in a theory journal because the people you want to reach is other theorists who are comfortable with math. You want to get down into the gritty details.

Your philosophy may be different, but the point is that it is about reaching your target audience not the impact factor.

Answer 3

I generally agree with the arguments made by @jakebeal and @MHH, and just want to make another point which the other answers don't state clearly. Within a field such as physics, some topics are more hot and receive more attention both within the field but also from other areas of science, which will translate into more citations. It is therefore common for some narrower journals that focus on hot topics to have higher impact factors than good, prestigious generalist journals that span the entire field. This is because generalist journals publish good science (hopefully) in both hot topics and all other subtopics, including subtopics that have lower citation rates (and e.g. theoretical work generally have lower citation rates, see also the answer from @MHH).

I don't know the journal ecosystem in physics, but can imagine that Physical Review Letters publish in all fields of Physics, while Advanced Energy Materials only publish in a narrower subfield, and this can be the reason for the difference in impact factor (which might not then correlate to the overall "prestige" in physics). A similar situation is found in the field of Ecology, where some journals related to Global change have higher impact factors than more traditional ecology journals with a broader scope, which arguably doesn't relate to a difference in journal prestige.

Answer 4

In my experience / research field, impact factor somewhat correlates with the prestige of the journal, but there can be exceptions (most notably when comparing across disciplines). Keep in mind that 'impact factor' is not the only metric, and may not even be the best metric. One may even get conflicting answers based on one's choice of metric. Here's an example to illustrate this point.

Based on impact factor:

Nature > Nature Materials > Physical Review Letters > Physical Review B.

Based on 2011 eigenfactor:

Nature > Physical Review Letters > Physical Review B > Nature Materials.

Based on Google Scholar's h5-index rankings:

Nature > Physical Review Letters > Nature Materials > Physical Review B.

So which metric is closer to the truth? It likely depends on who you ask, and it depends on which field they are in. Consider asking people from the research community you are in (and especially those who are in the places where you intend to apply for a job in future). Keep in mind that journal impact factor is not the only criteria. Other criteria that could be just as important (or even more important) include: referrals, who you worked with, what was your contribution to the paper, how well you are able to defend your work, whether your skills fit in with the rest of the organization, how established are you in the field.

Note: when talking to people, one should also consider that impact factor tends to be more controversial when comparing across fields (the eigenfactor system tries to correct for this). Some fields may have higher citation counts than others because: they tend to cite each other more often, there are more researchers, they publish more or often, or some combination of all 3. What happens when a particular department has people specialising in multiple fields (where some fields have significantly higher citation averages and journal impact factors than others)? Trying to equalise the playing field across multiple disciplines is not a straightforward task (and what happens if the department does not really try to equalise the playing field?).

Answer 5

Metrics to consider are (some already mentioned):

• Eigenfactor
• Article Influence
• Impact Factor
• 5 year impact factor
• Source-Normalized Impact per Paper (SNIP)
• SCImago Journal Rank (SJR)
• CiteScore
• H5 Index