How do I get my h index ?

This is a question which many researchers and even some managers quite often address to me. Here you go some simple procedures to find this kind of a “golden number” out. To a rapid calculation of your h index, please refer to the paragraph “Where do I find it?” below. If you want to add some culture, then continue to the next one.

Visibility and recognition

Do you remember my first post?. There I argued that scientific communication defines, at least in part, scientific activities. Your publications make your research visible and your scientific output can be measured through the analysis of published papers in peer-reviewed journals. Peer review means that the science that is published has been subjected to independent scrutiny and approved by qualified scientists, and thereby assures its quality and credibility.

Of course, there’re sources, bibliographic databases, that collect and organize the journals and the articles therein published. PubMed, CAS, Biological Abstracts to name a few.

Citations are often used as a means of evaluating the quality of publications—recognition by an author’s peers indicates that the scientific community acknowledges the work that has been published. To determine the number of citations a work has received and have an indicator of his importance bibliometric databases may be used. What differences bibliometric from bibliographic databases is that the former include, among other elements, the full list of bibliographic references of the articles they cover. So do Web of Science (WoS for short) and Scopus. Still another system, Google Scholar, relates its records translating bibliographic references into web links among the electronic version of the documents.

In 2005, the Argentina born physicist Jorge E Hirsch, professor at the University of California, San Diego mixed these two indicators, the number of published papers and the number of received citations to formulate an operator that combines both and named it the h (lowercase from Hirsch) index.

What is the h index?

The original definition of h index states:


“A scientist has index h if h of his or her Np papers have at least h citations each and the other (Np – h) papers have ≤h citations each”.

 So, if you have got a number of papers published and five of then have been cited five or more times, your h index is 5. It doesn’t matter if one of them has 30 citations or how many papers you’ve got.

Don’t ask how high your h index is. It depends, it allways depends. Let’s see on what.


 Where do I find it ?

The value

You can obtain the number either using bibliometric databases or some available calculators. In the first case, you just has to take a few steps with WoS or Scopus. Lest’s see how to in WoS

First, search for a name (yours or whoever). I’ve chosen Ismael Rafols, one of my colleagues.
Once you’ve got the list of results, click on “Create Citation Report” then

WoS Result list

Figure 1. The Web of Science list of records authored by Ismael Rafols

Look at the numbers on the right side of the graphics: the last one is the h index (in this case Ismael Rafols has, as of today, an index of 9).

citation report

Figure 2. The Citation Report for Ismael Rafols results and his h index

In the list of Rafols’ papers (Figure 3, below) you can see that paper #9 has received nine or more citations (ten actually) so, nine is the h index for this author.

Figure 3. An orange line marks the h index limit in the list of cited papers

With Scopus, things are slightly different. You perform an author search and,

Figure 4. Result of an author search in Scopus

once you’ve selected and maybe combine the right document sets, you can view a citation overview (not shown here)

Figure 5. The h index in Scopus

and then a graph showing where the citation frequency and publications lines intersect.

h index graph

Figure 6. The h index graph for Rafols’ papers in Scopus

h index calculators have proliferated but almost all have been superseded by Google Scholar Citations (GSC). This service, originally limited, is now open and anybody can use it providing he or she has a Gmail account (and obviously, has authored some paper or research document).

You can see by the Figure 7 that GSC provides a simple way for authors to keep track of citations to their articles. And it is an important statement. While the “official” h index is that WoS determines, GSC allows you to quickly identify who is citing or following your works (not just papers). Indeed, you don’t need to be in campus or to pay any kind of suscription to get an estimate of the impact of your work.

Figure 7. Google Scholar Citations report for Ismael Rafols

Needless to say that differences in the indexes calculated by each database arise precisely because the datasets, both in terms of documents covered and citations gathered, are different. Also, limitations in dates are important: Scopus do not cover citations before 1996 and GSC hardly contains documents prior to the 70s.

In the case I chose, Rafols has authored 32 papers covered by WoS or 24 covered by Scopus or 46 covered by GSC; the values for h index vary from 9 to 17. When a set of old physics papers are added, the lower limit rises to 13.

As usual, a whole set of limitations and drawbacks of h index have been identified. Also interesting is to note that practically nobody has referred to two complementary papers by Hirsch. However all criticism, my guess is that sooner or later, you’ll need to obtain it and put it on every form you fullfill to get something or somebody to investigate with. A new prove of the well known syndrome of “office blindness”.

Apologies for my English.

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