Interesting conversation at lunch today: topic was academic performance metrics and of course the dreaded citation index came up, with all its variants, flaws and systematics.
However, my attention was drawn to a citation metric which, on brief analysis, and testing, seems to be annoyingly reliable and robust. The H-score.
The H-score, takes all your papers, ranked by citation count; then you take the largest “k” such that the kth ranked paper has at least k citations.
So, you start off with a H-score of zero.
If your 5th highest cited paper has 5 citations but your 6th highest cited paper has 4 citations then your H=5.
If your 10th highest cited paper has 11 citations, but your 11th highest cited paper has 9 citations, then your H=10.
And so on. High H is better.
As you publish, your H-score should grow, but it becomes harder to get a higher H-score; in particular having one highly cited paper doesn’t help much, you need many papers cited a lot to get a good H-score. Publishing a lot of poorly cited papers doesn’t help either.
Crudely, the total number of citations increases as H2, with the normalization depending on the size of your sub-field (to get a lot of citation there must be a lot of papers published in your field!).
I was told that a mid-career theorist in my field typically has an H-score of 20-30, and sure enough I do, as do those of my near contemporaries that I quickly sampled. In fact the sample of half dozen recently tenured faculty theorists had remarkably tightly clumped H-scores.
A small sample of senior hot-shot faculty (full professors, well past tenure, at top ranked research universities) showed H-scores typically up around 50-60, breaking 30 is a big deal, seems to “get the ball rolling” where you have so many well cited papers that everyone starts citing you, because everyone else is citing you.
The highest H-score I found, searching sparsely on people I knew had phenomenal publication records, so not a complete sample, was 88.
Haven’t seen anyone in astro with H over 100, although I am sure someone in particle physics or some bio-subfield has done it.
Oh, and word is that people are using this metric to look at hires, faculty research progress, promotions etc. Certainly some people are…
This is an interesting issue – everyone agrees that citation impact is a very important metric.
Having highly cited papers is important, having lots of papers is important, and having many total citations is important.
But citations can be gamed; there is of course self-citation, which is easily filtered; there is citation-by-progeny – researchers who produce many students or postdocs tend to build up a loyal citation base. There is the issue of normalized citation – the total citation divided by the number of authors, which is probably over-harsh, but a lot of the most heavily cited papers are from large teams or surveys with large co-author groups.
There are definitely citation circles out there, mostly informal or spontaneous; and there are anti-citation groups – authors who refuse to cite relevant papers by competitors for a variety of interesting reasons.
Because of all this, most citation measures are very frustrating; but of the ones I have heard of to date, the H-score at a quick glance seems the most robust and interersting.
PS: I hear the concept was invented by a (physical?) scientist at a UC, possibly UCSB.
Someone tip me to who it was if they know so I can cite them!
Google didn’t help, there is some sort of protein match test which has a “H-score” which swamps and search pattern I’ve thought of.
Ah, here we go: from Lattice QCD in the comments:
“The originator of the h-index is Jorge E. Hirsch of UCSD, a condensed matter theorist. The paper in which he proposed the h-index is arXiv:physics/0508025“
The Hirsch index.
Ed Witten has H=110, Heeger has H=107
Just to give a sense of what is involved: in my field, a paper by Frazer Pearce a few years ago estimated that about one published paper in 100 has 100 citations in the first five years after publication.