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Introduction
Researchers aim to publish in the highest-ranking journal possible to enable wider dissemination and for career advancement. Journals are ranked in many ways (table 1), but scientific quality is not important for these rankings.
An excellent example is a now retracted paper looking at a possible link between the MMR vaccine and autism. This was published in one of the highest Impact Factor journals in the world, and was subsequently found to be fraudulent. Prior to full retraction, it had gained 3,563 citations, which increased the standing of that journal. We have not cited this paper as we do not wish to increase the visibility of the work.
Ranking methods
Impact factor (IF) was one of the first critical evaluation systems developed to check journal quality, created in 1955.1 The 2-year journal impact factor is the ratio between the number of citations received in that year for publications in that journal that were published in the two preceding years and the total number of ‘citable items’ published in that journal during the two preceding years.2 The highly cited journals have IFs above 50. The immediacy index performs a similar calculation, but only uses data from the last complete year.
The cited half-life is the number of years accounting for half of the current citations received by a journal. It can vary with several factors, for instance older journals will trend to a higher cited half-life.
H-index, or Hirsch’s Index, can rank individual …
Footnotes
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Correction notice This paper has been amended since it was published online. The second paragraph of the introduction about a retracted paper has been rewritten. Also, in the section 'Ranking methods', the third sentence which refers to highly cited journals has been changed to 'The highly cited journals have IFs above 50'.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.