What’s an h-index?

In academic research, the term h-index has been recently used a lot. So what does it mean?

Basically it is a way to evaluate the scientific impact of venues (e.g. conferences) and academics (e.g. researchers).

The h-index of A (where A is a venue or an academic) is the maximum X, where A has X papers cited at least X times.

I am not a mathematics guru but that’s frankly the best way to explain it. So a researcher with 100 publications, where the maximum number of citations per paper he got was 2, would have an h-index of 2, because he has 2 papers cited at least 2 times, but there’s no third paper cited 3 or more times. While another one who has 10 publications, each cited 10 or more times, would have an h-index of 10. A third researcher who has 7 publications cited 2 times each, a publication cited 20 times, and another 3 cited 10 times each, would have an h-index of 4, because only 4 of the publications are cited 4 or more times, but there is no fifth paper that was cited 5 or more times.

It’s a bit complicated I know, if you want to know your h-index, you can just create a Google scholar account and it will do it for you, after you specify which publications are yours.

So why is this a better way to evaluate the impact of an academic or a venue than simply counting the number of publications or the number of citations? Well, if it was based on the number of publications, you could just publish a lot of papers at venues that accept everything.. If it was based on the number of citations, you could have 1k citations because of a small contribution to someone else’s paper, that resulted in you being a co-author. In the latter situation, it could be that your impact is not strong after all, perhaps the rest of your publications have very few citations (or none). If that was your only publication, your h-index would be 1. Do you see the point now?

Bonus fact: The h5-index is basically the same as the h-index, but limited to the last 5 years.

Venues have h-indexes too, as you might have guessed, it’s also calculated the same way based on the publications published at that venue. Today the h5-index of CHI, the number one conference in Human Computer Interaction, is 78. You can also check that out on Google Scholar’s venue search. The h-index can give you insights about the strength of the conference, the exposure its papers get, etc..