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Researchers: Bibliometrics tools and measures

Exploring citations in journal indexing databases

  • HeinOnline: This source now has cited by features to indicate articles that have been cited in other articles. 
  • Institute of Physics (IoP): The abstracts for articles in IoP journals will often contain links to All Citing Articles.
  • JSTOR. JSTOR notes when an article has been cited by other articles in the JSTOR database. Look for a tab reading Items Citing this Item on the Article Information page. JSTOR also allows you to check for citations in the GoogleScholar database.
  • ProQuest. A number of databases previously available through CSA (including ERIC) are now in Proquest. They provide lists of references used by an article and how often a particular reference has been cited by other articles in the same database.
  • ScienceDirect. Article abstracts in ScienceDirect frequently include provide totals of citing articles derived from Scopus.

Plus, there is Google Scholar, and watch out for cited by information on journal publisher's platforms.

ORCiD

ORCID logo

What is an ORCiD?

ORCiD is a unique identifier system that has been adopted across the world. Not only does it allow you as a researcher to distinguish yourself as 'you' - an ORCID also supports linking systems involved in key research workflows.

Find out more about ORCID and sign-up here: http://orcid.org/

h-index variants

Variants based on the h-index include:

  • Contemporary h-index - see separate box on this page
  • i10 index - number of publications with 10 or more citations
  • g-index - a more complex and less common measure, explained in a blogpost.
  • m-quotient - divides the h-index by the number of years a scientist has been active

From the published literature, it seems that it is best not to rely on a single type of index but to use a variety of them. 

Further reading: Bornmann, L., Mutz, R. and Daniel, H.-D. (2008), Are there better indices for evaluation purposes than the h index? A comparison of nine different variants of the h index using data from biomedicine. J. Am. Soc. Inf. Sci., 59: 830–837. doi:10.1002/asi.20806

This bibliometrics page will explore

**Please click on any word that is a link, to find out more about it in the accompanying glossary or in a further source of information.**

This page looks at two ways of using bibliometrics:

  1. Journal or serial publication measures
  2. h-index and other similar scores for a researcher

Bibliometrics are used at other levels, eg at individual research output level or for a whole research institute. 

1. Journal or series level measures

There are various measures and tools which you can use, including the h-index which is dealt with separately in this guide. The other main measures for journals and serial publications are:

Measure Description of measure Access
SCImago Journal Rank Citations are weighted depending on citing source's own score. Based on Elsevier's Scopus data. Free to use
SNIP Scores are normalised for the field and citation potential of a journal's papers. Based on Elsevier's Scopus data. Free to use
Impact Factor Measure published each year and based on the previous 2 years' citations. Also a 5 year version available, along with other variants. Based on Thomson Reuters' data. Purchase as part of Web of Science

The Impact Factor has been heavily criticised, especially recently in Nature but it is worth understanding, in order to appreciate the value of alternatives. It is a score that is created by taking:

  1. citations in 2014, to papers in the journal that have been published in the previous 2 years
  2. total number of papers in the journal, published in 2014

"a" divided by "b" is what gives you your impact factor for 2014, which would be published in 2015.

2. h-index

This measure is based on citation counts and highly adaptable: it can be applied to any collection of papers and based on any set of data. SCImago give an h-index for journals. Many sources give an h-index for an author, and some research institutes calculate one for a whole team. The same author might have a different h-index on different sites or tools which use different citation tracking data sources, so perhaps find your highest one!

The h-index is the: 

number of articles in the collection (h) that have received at least (h) citations over the whole period. 

The h-index is not skewed by a single highly cited paper (which a simple citation count would be), nor increased by a large number of poorly cited publications (which a count of publications would be).

As an academic author you will probably have a Google Scholar profile where you can see your h-index. You may also have profiles on Scopus or other sites which may display an h-index. The easiest way to manage these profiles is to use ORCID.

ORCID and Scopus

SCImago Journal Rank (SJR)

SJR's weighting of scores enables more differentiation between journals and is representative of a journal’s influence. SJR:

expresses the average no. of weighted citations received in the selected year by the documents published in the journal in the three previous years

The SCImago website is well worth exploring: there is also a country rank and there are visualisation tools. For journals it is possible to search for or filter journals by subject area, for example. The filter for Open Access (OA) journals is useful. 

Journals are displayed in a table which provides many columns of data, including:

  • the SJR
  • the quartile that that SJR falls into
  • the h-index
  • raw totals of documents published
  • average citations per document. 

 

SNIP - Source normalised impact per paper

This score comes from the CWTS at Leiden University, Netherlands. It is:

the number of citations given in the present year to publications in the past three years divided by the total number of publications in the past three years.

A single citation in a subject area where citations are rarely made will have a higher influence on the overall SNIP. Stability intervals show you how accurate the score is thought to be: the narrower the interval, the more confidence there is in the score. There are published papers explaining the way the score is calculated.

Manually calculating the h-index

It is possible to manually calculate the h-index by listing each of the publications in a table which might look something like this:

Number No. of citations received
1 30
2 18
3 12
4 8
5 4
6 2
7 1
8 0
9 0
10 0

In this table, we can see that the h-index is 4, and that if paper number 5 had just one more citation then the h-index would be 5. Indeed, some sources like Scopus produce an h-graph for you to see such data visually, for an author's h-index.

Contemporary h-index

On the website Publish or Perish you can find a tool to calculate a "contemporary h-index". This is one of a number of variants on the h-index. In this variant, the more recent citations are weighted more heavily in the final score:

  • For an article published during the current year, its citations account 4 times
  • For an article published 4 years ago, its citations account only 1 time
  • For an article published 6 years ago, its citations account 4/6 times
  • … and so on.