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Introduction to Bibliometrics

Bibliometrics is a set of methods used to analyze the impact and distribution of scientific publications within academic community.
Bibliometrics offers a quantitative methods for research evaluation that must be considered always as  support to qualitative methods, the so-called peer-review.
What can bibliometrics measures:

  • The impact of scientific journals (it determines which are the most influential journals for each desciplinary subject);
  • The impact of every single article;
  • The impact of researcher’s activity.

The most widely used bibliometric indicators are:

Impact factor (IF)

It measures the importance of a journal within a subject category. According to this indicator, the more the IF is higher, the more the journal is influential.
A journal impact factor is a measure of the frequency with which the average article in a journal has been cited in a particular year. For example:
Journal Impact Factor =

Cites in 2012 to articles published in Journal X in 2011 and 2010
Total number of articles published in Journal X in 2011 and 2010

The IF is published every year by Thomson Reuters in Journal Citation Reports and it’s not freely available.


h-index, created in 2005 by Jorge E. Hirsch, is a bibliometric indicator that measures both productivity and impact of the published work of a researcher. An author with an index of h has published h papers each of which has been cited in other papers at least h (for example, if you have published one article that has received at least one citation, your h-index is one).

The h-index has several advantage as:

  • It measures the quality of your paper based on the number of citations, and not on the journal in which is published;
  • It’s good for comparing researchers within a disciplinary area at similar stages in their careers;
  • It may be used to compare not just individuals, but also departments, programs or any other group of scientists.

The h-index is a free indicator and it can be calculated with the software Publish or Perish ( PoP), or with  Scholarometer, an extension for Firefox and Chrome.

Alternative indicators

 The Eigenfactor another free indicator that offers a mathematical model to calculate the impact of scientific journals. The Eigenfactor score of a journal is an estimate of the percentage of time that library users spend with that journal. The Eigenfactor algorithm corresponds to a simple model of research in which readers follow chains of citations as they move from journal to journal.

 Altmetrics are new metrics proposed as an alternative to the widely used journal impact factor and personal citation indices like the h-index. Altmetrics cover not just citation counts, but also other aspects of the impact of a work, such as how many data and knowledge bases refer to it, article views, downloads, or mentions in social media and news media. For more information, see the  related pageon Wikipedia.

In addition to the above mentioned indicators, are available many disciplinary journal rankings created by institutions and associations, that can be used in many ways. These lists are important especially for the evaluation of non-bibliometric areas (arts and humanities), or when other indicators are not available.

Bibliometrics in IMT Library

IMT Library supports Research Planning and Organization Office and Human Resources Office in the activity of research evaluation for what concerns quantitative evaluation.

The Library staff analyzes the publications of the faculty providing tables and graphs for the purposes of the evaluation activity of IMT.
If you want more information or if you need assistance in the use bibliometric indicators, please contact us at