Bibliometrics aren’t just useful for analyzing who’s being cited; they are also pretty good at telling you who’s not being cited, too.

Today, we’ll look at professors whose H-index (see here for a reminder of how it is calculated) is zero – that is, professors who have either never been published or (more likely) never been cited.

There are three reasons why a scholar might have an H-index of zero. The first is age; younger scholars are less likely to have published, and their publications have had less time in which to be cited. The second is prevailing disciplinary norms. there are some disciplines – English/Literature would be a good example – where scholarly communication simply doesn’t involve a lot of citations of other scholars’ work. The third is simply that a particular scholar might not be publishing anything of particular importance, or indeed publishing anything at all.

Let’s take each of these in turn. We can examine the first two questions pretty easily just by looking at the proportion of scholars with zero H-indexes by rank and field of study (our database has data on the rank of a little over three-quarters of academic staff in it – about 47,000 of the people in total, which is a pretty good sample).

Proportion of Academic Staff without a Cited Publication, by Rank and Field of Study

Surprised? So were we. Not because of the differences across ranks (H-index scores are necessarily positively correlated with length of career) or across fields of study (we did this one already0. What really blew us away was the number of full professors who have never had a paper cited, especially in the sciences. Who knew that was even possible?

So, what about that third reason? It is obviously difficult to generalize, but one should note that even within disciplines, there are some enormous gaps in publication/citation rates. In economics as a whole, 15.6% have an H-index of zero, but the proportion of economists in any individual economics department with an H-index of zero varies between 0% and 63%. In biology (disciplinary average: 7.7%), individual departments range between 0% and 60%; in history (disciplinary average: 13.4%), the range is between 5% and 50%. It is vanishingly unlikely that these differences are solely the result of different departmental age profiles; more likely, they reflect genuine differences of scholarly strength.

Now, there’s nothing saying all professors need to be publishing machines. But if that’s the case, maybe not all professors need to have 2/2 or 2/1 teaching loads to conduct all that impactful research, either. Running a university requires trade-offs between research and teaching: bibliometric analysis such as this is a way to make sure those trade-offs are well-informed.