Understanding the Scientific Publication “H” Index, and others

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How to evaluate the academic performance of individual scientists

[By Dr. David Edward Marcinko MBA]

Dr. MarcinkoThe “h-index” was introduced in 2005 as a metric for estimating “the importance, significance and broad impact of a scientist’s cumulative contributions.” It takes into account both the number of an individual’s publications and their impact on peers, as indicated by citation counts.


Its creator, Jorge Hirsch (UC-San Diego) asserts that a “successful scientist” will have an h-index of 20 after 20 years; an “outstanding scientist” will have an index of 40 after 20 years; and a “truly unique individual” will have an index of 60 after 20 years or 90 after 30 years. You can read more about it in Nature and PhysicsWeb.

Web of Science

Curious to know your own h-index? You can easily determine it using Web of Science. Select “Science Citation Index Expanded.” Click “General Search” category and search for your name as author (e.g., SMITH J*). Use “Refine Your Results” by Institution to differentiate yourself from other scientists with the same initial(s). (This is an important step, otherwise your publications will be intermingled with unrelated papers and your h-index will be inaccurate.) Click on “Citation Report” in the box on the right side. Your h-index will be calculated automatically.

An alternative method is to sort your citations by “Times Cited”, using sort box on the right side. Scan down the list until the number of the paper exceeds the number of citations to that paper. For example, your h-index is 20 if your 21st paper has been cited 20 or fewer times, but your 20th paper has been cited 20 or more times.


Although effective and simple, the h-index suffers from some drawbacks that limit its use in accurately and fairly comparing the scientific output of different researchers. These drawbacks include information loss and low resolution: the former refers to the fact that in addition to h2 citations for papers in the h-core, excess citations are completely ignored, whereas the latter means that it is common for a group of researchers to have an identical h-index.


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Fixing the Bias

To solve these problems, Chun-Ting Zhang proposed the “e-index“, where e2 represents the ignored excess citations, in addition to the h2 citations for h-core papers. Citation information can be completely depicted by using the h-index together with the e-index, which are independent of each other. Some other h-type indices, such as a and R, are h-dependent, have information redundancy with h, and therefore, when used together with h, mask the real differences in excess citations of different researchers.

Link: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0005429


Google Scholar is another useful source of citation data.  A.-W. Harzing’s Publish or Perish software is a free application for Windows, Mac OS, and GNU/Linux that uses Google Scholar to compute citation counts, h-indexes, journal impact factors, and many other citation metrics.


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Speaker: If you need a moderator or speaker for an upcoming event, Dr. David E. Marcinko; MBA – Publisher-in-Chief of the Medical Executive-Post – is available for seminar or speaking engagements. Contact: MarcinkoAdvisors@msn.com


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2 Responses

  1. More Metrics

    In addition to the various simple statistics (number of papers, number of citations, and others), Publish or Perish calculates the following citation metrics (see Citation metrics in the online help file for more details):

    Hirsch’s h-index Proposed by J.E. Hirsch in his paper An index to quantify an individual’s scientific research output, arXiv:physics/0508025 v5 29 Sep 2005. It aims to provide a robust single-number metric of an academic’s impact, combining quality with quantity.

    Egghe’s g-index Proposed by Leo Egghe in his paper Theory and practice of the g-index, Scientometrics, Vol. 69, No 1 (2006), pp. 131-152. It aims to improve on the h-index by giving more weight to highly-cited articles.

    Zhang’s e-index Publish or Perish also calculates the e-index as proposed by Chun-Ting Zhang in his paper The e-index, complementing the h-index for excess citations, PLoS ONE, Vol 5, Issue 5 (May 2009), e5429. The e-index is the (square root) of the surplus of citations in the h-set beyond h2, i.e., beyond the theoretical minimum required to obtain a h-index of ‘h’. The aim of the e-index is to differentiate between scientists with similar h-indices but different citation patterns.

    Contemporary h-indexProposed by Antonis Sidiropoulos, Dimitrios Katsaros, and Yannis Manolopoulos in their paper Generalized h-index for disclosing latent facts in citation networks, arXiv:cs.DL/0607066 v1 13 Jul 2006. It aims to improve on the h-index by giving more weight to recent articles, thus rewarding academics who maintain a steady level of activity.

    Age-weighted citation rate (AWCR) and AW-indexThe AWCR measures the average number of citations to an entire body of work, adjusted for the age of each individual paper. It was inspired by Bihui Jin’s note

    The AR-index: complementing the h-index, ISSI Newsletter, 2007, 3(1), p. 6. The Publish or Perish implementation differs from Jin’s definition in that we sum over all papers instead of only the h-core papers.Individual h-index (original)

    The Individual h-index was proposed by Pablo D. Batista, Monica G. Campiteli, Osame Kinouchi, and Alexandre S. Martinez in their paper Is it possible to compare researchers with different scientific interests?, Scientometrics, Vol 68, No. 1 (2006), pp. 179-189. It divides the standard h-index by the average number of authors in the articles that contribute to the h-index, in order to reduce the effects of co-authorship.Individual h-index (PoP variation)

    Publish or Perish also implements an alternative individual h-index called hI, norm that takes a different approach: instead of dividing the total h-index, it first normalizes the number of citations for each paper by dividing the number of citations by the number of authors for that paper, then calculates the h-index of the normalized citation counts. This approach is much more fine-grained than Batista et al.’s; we believe that it more accurately accounts for any co-authorship effects that might be present and that it is a better approximation of the per-author impact, which is what the original h-index set out to provide.

    Multi-authored h-index. A further h-like index is due to Michael Schreiber and first described in his paper To share the fame in a fair way, hm modifies h for multi-authored manuscripts, New Journal of Physics, Vol 10 (2008), 040201-1-8.

    Schreiber’s method uses fractional paper counts instead of reduced citation counts to account for shared authorship of papers, and then determines the multi-authored hm index based on the resulting effective rank of the papers using undiluted citation counts. Average annual increase in the individual h-index

    As of release 4.3 Publish or Perish also calculates the average annual increase in hI,norm, called hI,annual. This average annual increase in the individual h-index is useful for the following reasons:

    • In common with the hI, norm index, it removes to a considerable extent any discipline-specific publication and citation patterns that otherwise distort the h-index.
    • It also reduces the effect of career length and provides a fairer comparison between junior and senior researchers.

    The hI, annual is meant as an indicator of an individual’s average annual research impact, as opposed to the lifetime score that is given by the h-index or hI, norm.

    Hope R. Hetico RN MHA


  2. Dr. Marcinko and Professor Hetico,

    Many thanks for this ME-P. I have been looking for this type of info to no avail; and appreciate all your work.

    Professor Kilgore


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