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Impact Measures and Published Scholarship - Evansville: Definitons

Definitions

5-Year Journal Impact Factor – “The average number of times articles from the journal published in the past five years have been cited in the JCR year. It is calculated by dividing the number of citations in the JCR year by the total number of articles published in the five previous years.”  (Thomson Reuters)

Altmetrics – “New metrics proposed as an alternative to the widely used journal impact factor and personal citation indices like the h-index. The term altmetrics was proposed in 2010, as a generalization of article level metrics, and has its roots in the twitter #altmetrics hashtag. Although altmetrics are often thought of as metrics about articles, they can be applied to people, journals, books, data sets, presentations, videos, source code repositories, web pages, etc. 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.”  (Wikipedia)

Article Influence® Score – “Determines the average influence of a journal’s articles over the first five years after publication.  It is calculated by dividing a journal’s Eigenfactor Score by the number of articles in the journal, normalized as a fraction of all articles in all publications.  This number is roughly analogous to the 5-Year Journal Impact Factor in that it is a ratio of a journal’s citation influence to the size of the journal’s article contribution over a period of five years.”  (Thomson Reuters)

Cited Half-Life – “The median age of the articles that were cited in the JCR year. Half of a journal's cited articles were published more recently than the cited half-life. For example, in JCR 2001 the journal Crystal Research and Technology has a cited half-life of 7.0. That means that articles published in Crystal Research and Technology between 1995-2001 (inclusive) account for 50% of all citations to articles from that journal in 2001.  Only journals cited 100 or more times in the JCR year have a cited half-life.”  (Thomson Reuters)

Eigenfactor® Score – A calculation “based on the number of times articles from the journal published in the past five years have been cited in the JCR year, but it also considers which journals have contributed these citations so that highly cited journals will influence the network more than lesser cited journals.  References from one article in a journal to another article from the same journal are removed, so that Eigenfactor Scores are not influenced by journal self-citation.” (Thomson Reuters)

h-index – “An index that attempts to measure both the productivity and impact of the published work of a scientist or scholar. The index is based on the set of the scientist's most cited papers and the number of citations that they have received in other publications. The index can also be applied to the productivity and impact of a group of scientists, such as a department or university or country, as well as a scholarly journal. The index was suggested by Jorge E Hirsch, a physicist at UCSD, as a tool for determining theoretical physicists’ relative quality and is sometimes called the Hirsch index or Hirsch number.”  (Wikipedia)  “The h-index of a publication is the largest number h such that at least h articles in that publication were cited at least h times each. For example, a publication with five articles cited by, respectively, 17, 9, 6, 3, and 2, has the h-index of 3.”  (Google Scholar)

  • h5-index – “The h-index for articles published in the last 5 complete years. It is the largest number h such that h articles published in 2008-2012 have at least h citations each.”  (Google Scholar)
  • h5-median – “The median number of citations for the articles that make up its h5-index.”  (Google Scholar)
  •  i10-Index – “The number of academic publications an author has written that have at least ten citations from others. It was introduced in July 2011  . . . as part of their work on Google Scholar.”  (Wikipedia)

Immediacy Index – “The average number of times an article is cited in the year it is published.

  • The journal Immediacy Index indicates how quickly articles in a journal are cited.
  • The aggregate Immediacy Index indicates how quickly articles in a subject category are cited.
  • The Immediacy Index is calculated by dividing the number of citations to articles published in a given year by the number of articles published in that year.” (Thomson Reuters)

ISI – Institute for Scientific Information, original producer of the Journal Citation Reports®, currently produced by Thomson Reuters.

Journal Impact Factor – “the average number of times articles from the journal published in the past two years have been cited in the JCR year.  The Impact Factor is calculated by dividing the number of citations in the JCR year by the total number of articles published in the two previous years. An Impact Factor of 1.0 means that, on average, the articles published one or two years ago have been cited one time. An Impact Factor of 2.5 means that, on average, the articles published one or two year ago have been cited two and a half times.” (Thomson Reuters)

ORCid – An open, non-profit, community-driven effort to create and maintain a registry of unique researcher identifiers and a transparent method of linking research activities and outputs to these identifiers. (ORCID.org)

Percentage of Self Citation – The percentage of self citations of a source, calculated as the percentage of all citations given in the present year to publications in the past three years that originate from the source itself. (CWTS Journal Indicators)

Raw Impact per Publication – Average number of citations per publication.  (CWTS Journal Indicators)

SCImago Journal Rank (SJR) – "a measure of the scientific prestige of scholarly sources.  SJR assigns relative scores to all of the sources in a citation network.  Its methodology is inspired by the Google PageRank algorighm, in that not all citations are equal.  A source transfers its own 'prestige', or status, to another source through the act of citing it.  A citation from a source with a relatively high SJR is worth more than a cittion from a source with a lower SJR." http://www.journalmetrics.com/faq.php

Source Normalized Impact per Paper (SNIP) – "measures contextual citation impact by weithting citations based on the total number of citations in a submect field.  SNIP is the ratio of a source's average citation count per paper, and the 'citation potential' of its subject field.  It aims to allow direct comparison of sources in different subject fields."  http://www.journalmetrics.com/faq.php

Stability Indicator – A stability interval reflects the stability or reliability of an indicator. The wider the stability interval of an indicator, the less reliable the indicator. If for a particular source RIP and SNIP have a wide stability interval, the indicators have a low reliability for this source. This for instance means that the indicators are likely to fluctuate quite significantly over time. CWTS Journal Indicators employs 95% stability intervals constructed using a statistical technique known as bootstrapping. (CWTS Journal Indicators)