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Scholarly Publication: Measuring Impact


Citation counts

Databases that provide citation counts include:

Links of Interest

The h-index

scattergraph showing h-indexAn author's h-index, or Hirsch index, is the number (integer) n for which the author has published at least n papers which have each been cited at least n times.  Eg

  • 5 papers cited 1, 2, 3, 4, 5 times: h-index is 3 (3 papers cited at least 3 times)
  • 5 papers cited 1, 1, 2, 2, 2 times: h-index is 2 (at least 2 papers cited 2 times)
  • 5 papers cited 1, 1, 1, 1, 20 times: h-index is 1 (at least 1 paper cited 1 time)

Journal impact factors

Impact factors attempt to measure the importance of a journal based on how often its articles are cited in the field.

SNIP (Source Normalized Impact Per Paper)

  • Measures the average citation impact of the publications in a journal. Corrects for differences in citation practices between scientific fields. Based on Scopus data. 

SCImago Journal and Country Rank

  • Ranks journals indexed in Scopus from 1996 based on an indicator developed from Google's PageRank algorithm.Key indicator is know as SCImago Journal Rank Indicator (SJR). Includes approx.20,000 journals in 313 subject specific categories


  • Based on the theory that a single citation from a highly ranked journal should count more than mulitple citations from a lower ranked title. Uses Thomson Reuters data for approximately 12,000 journals. Read the Eigenfactor FAQs

Google Scholar Metrics

  • Provides h5-index and h5-median for  the top 20 journals in 267 subject categories.

Publish or Perish

  • Based on Google Scholar metrics this free software can calculate a variety of author metrics.


Obvious factors can heavily influence journal impact factors, such as journal title changes, or publishers gaming the system by requiring authors to cite articles from other journals by the same publisher.  However there are more systematic problems:

  • Review articles are often widely cited, so review journals tend to top the lists.
  • Citations based on a single publisher's dataset means the factors include all the limitations of ordinary citation counts. Compare multiple tools.
  • Wide variations between different research fields inherent to the different patterns of publication in those fields.
  • Higher impact journals tend to have higher retraction frequencies [source]

What are altmetrics?

  • a measure of the amount of exposure based on web activity, including download counts, page views, mentions in news reports, social media, blogs,
  • altmetrics (alternative + metrics) are complementary to conventional article-level metrics like journal impact


What are altmetrics?

Scholars seek better ways to track impact online

Where to find altmetric measures?

Symplectic Elements - as well as standard metrics such as SNIP and SJR,  Elements provides Altmetrics e.g. number of times an output has picked up by news outlets, tweets, blogs, Mendeley, CiteULike, Facebook etc

Ebsco databases (e.g PsycInfo, Business Source Complete) now include PlumAnalytics

Web of Science provides download statistics for articles

Some journal web-sites also provide altmetric statistics

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