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Research impact and visibility: Measuring impact

Impact

What impact can be measured?                                                                                                                                                            

  • individual, group, institution, subject area, geographic region                                  
  • article level (altmetrics)
  • publication channel methods:                                                                                                                     
  1. quantitative - journals, e.g. Impact Factor
  2. qualitative - journals, series, conferences, publishers, e.g. Publication Forum (Jufo)

Author impact

H-index (Hirsch-index) measures and compares researchers´ scientific publication output.

Citation databases contain citation information and the linkages between citing articles - who has cited which article - and enable the calculation each researcher´s h-index.

How to calculate H-index

  • Sort the publications from largest to smallest (based on the number of citations).
  • Find the last position where number of citations is greater or equal to the position.

Typical of H-index

  • The more highly cited publications the researcher has, the greater his/her h-index.
  • H-index favours researchers with a long career. H-index cannot decrease.
  • H-indexes should be compared only within a certain field of science.

Citation databases Web of Science, Scopus and Google Scholar have each their own h-indexes. Google Scholar´s h-index  counts non-scientific publications like master's theses, too. Furthermore, part of the publications are duplicates because of self-archiving. Google Scholar´s h-index differs significantly from those of WoS and Scopus.

h-index quick guides

An index of g means that your g most highly-cited articles together have at least g-squared citations.

Typical of G-index

  • The g-index weights highly-cited papers more heavily.
  • Your g-index will always be equal to or greater than your h-index.
  • Publish and Perish software counts g-index for researchers and journals.

The citation report (WoS) / overview (Scopus) provides aggregate citation statistics like:

  • total number of publications found
  • total number of times all publications have been cited (also without self-citations)
  • average number of times a publication has been cited (only in WoS)
  • h-index (Hirsch-index) additionally
  • Scopus article level metrics (Mendeley Readers, Blos posts, Tweets...)
  • WoS usage count per article (last 180 days / since 2013); Highly Cited Papers, Top Papers, Hot Papers
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Journal impact

Publication Forum (in Finnish often referred to as JUFO) evaluates Finnish and foreign academic publication channels. Publication Forum operates under the auspices of the Federation of Finnish Learned Societies (TSV).

Publication Forum ratings

  • disseminate information on the impact and prestige of the scientific publication channels
  • handle humanities and social sciences more equally than citation analyses
  • are meant to evaluate large publication volumes only, not suited for the evaluation of the merits of an individual researcher
  • are updated regularly
  • the review of ratings is done once every four years by 23 field specific panels

The three-level classification rates the major foreign and Finnish publication channels of all disciplines.

Journal Citation Reports is a part of  the Web of Science database which tells the journal impact factors (JIF).

Impact Factor score

  • tells the average number of citations for each article in the journal 
  • based on two-year citation data - available five-year citation data
  • can be provided without journal self-cites
  • differences in citation patterns among disciplines are not considered
  • all citations are weighted equally regardless of the prestige of the citing journal
  • is not meant for evaluating an individual researcher

 

                       Impact factor

SJR, SNIP and CiteScore can be seen in the context of Scopus journals (Sources - Browse sources). You can compare sources.

SJR indicator (SCImago Journal Rank)

  • measures the scientific prestige of a journal among other journals
  • estimates the journal impact as the average number of weighted citations for each article in the journal
  • weights citations based on the prestige of the citing journal
  • calculated using citation data from Scopus
  • based on three-year citation data
  • takes into account all types of journal articles, not only research and review articles
  • normalizes for differences in citation behavior between subject fields
  • max 33 % journal self-citations are included

SNIP indicator (Source Normalized Impact per Paper)

  • measures the contextual citation impact of a journal
  • based on Scopus data
  • based on three-year citation data
  • takes into account research articles, review articles and conference articles, but not all publication types unlike JIF 
  • differences in citation patterns among disciplines are considered
  • possible to compare journals from different disciplines unlike JIF
  • journal self-citations are included

CiteScore

  • based on Scopus data
  • an alternative to Impact Factor
  • three-year citation window
  • besides articles and reviews takes into account in calculation also other document types such as letters or editorials

 

How to calculate CiteScore

             CiteScore

A journal has an h-index of h if there are at least h papers published in that journal that have received at least h citations each.

Typical of journal h-index...

  • an alternative to Impact Factor, opens up the possibility of evaluating the impact of a journal that is not part of the Web of Science database
  • no defined citation window
  • a rough estimate for the productivity of a journal over a long time period
  • not influenced by the fact that a few articles might have a large number of citations
  • the amount of articles a journal has published will affect somewhat the h-index score, a journal that publishes many articles will most likely get a higher h-index score
  • preferable for comparing journals within the same discipline

Journal Citation Reports also publishes Article Influence scores and Eigenfactor scores.

Article Influence (AI) score

  • tells the average impact of an article published in a journal from a five-year period after the publication of the article
  • comparable with the Impact Factor
  • calculated by dividing the Eigenfactor score of the journal by the number of articles published

Eigenfactor (EF) score

  • describes journal's total impact and is not comparable with Impact Factor
  • citations also from other sources than Thomson Reuters journals, e.g. books
  • 5 year citation window
  • adjusts differences in citation patterns among disciplines
  • accounts for difference in prestige among citing journals 
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