Humbug, Hirsch’s h-index! The humbling yet heartwarming hooligan, happily hopping homeward.
Many people have issues with the widespread use of the h-index in determining one’s scientific worth. But the h-index is not inherently bad; it simply needs to be considered in the context of one’s field and seniority. Even in a given field, the h-index is higher for the hot, fast-moving topics than for the slower ones. Also, it tends to be high in larger fields and, more generally, in fields in which the number of papers published per unit time is high. For instance, brilliant mathematicians will have much, much smaller h-indices than brilliant biomedical engineers or chemists. While some people like to compare the h-indices too broadly, between fields with vastly different dynamics, as it makes them feel superior or something, that’s just silly; I think (hope?) that most reasonable people understand this fallacy in the use of the h-index.
However, I want to discuss the use of the h-index for very junior folks. The h-index can certainly emphasize that an individual is unusually creative or high-impact, but let’s face it: unless we are dealing with math or theoretical physics or another endeavor where the intellectual labor of a single individual spawns a paper, it’s the teams, and sometimes very large ones, that are behind each paper in the physical and biological sciences. If you are in a productive, successful group, where people are not particularly stingy about co-authorship, you can achieve a pretty high h-index largely by association.
A couple of years ago, we were selecting from among several candidates for the department best-dissertation awards. The award went, against my protests, to a young person who had the highest h-index. Mind you, the h-index was high because this person did research in a great group as an undergrad, and had a number of papers where they were author number 7 or 8 among about 15; then they were a member of a team in grad school, where again there were many papers with the person author number 4 or 5. Now compare this with the work of someone who had 5 or 6 first-author publication in the last two years of their PhD. These papers were fewer in number and likely not highly cited at the point of graduation, owing to the short time (most just got out when we considered the award nominees). In contrast, the well-plugged-in first person had a fairly high h-index, as they were part of strong and prolific groups for a long time, making a minor contribution to each paper, but the papers were more numerous and out for longer and had the time to get cited (in case you are wondering, that person only had one first-author paper).
Anyway, h-index is not evil, it’s a just number. It’s the people who can be misinformed, lazy, or simply self-serving and manipulative in how they utilize it. Then again, people would abuse any other available metric as well; at least this one is transparent and easy to calculate.