Immediacy index

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An immediacy index is a measure of how topical and urgent work published in a scientific journal is. Along with the better known impact factor measure, it is a calculated each year by the Institute for Scientific Information (ISI) for those journals which it indexes; both impact factors and immediacy indices are published annually in the Journal Citation Reports.[1][2]


The immediacy index is calculated based on the papers published in a journal in a single calendar year. For example, the 2005 immediacy index for a journal would be calculated as follows:

A = the number of times articles published by the journal in 2005 were cited in indexed journals during 2005
B = the number of articles, reviews, proceedings or notes published by the journal in 2005
2005 immediacy index = A/B

As with the impact factor, there are some nuances to this: for example, ISI excludes certain article types (such as news items, correspondence, and errata) from the denominator.[1][2][3]


  1. ^ a b "Bibliometrics (journal measures)". Elsevier. Retrieved 2012-07-09. a measure of the speed at which content in a particular journal is picked up and referred to 
  2. ^ a b "Glossary of Thomson Scientific Terminology". Thomson Reuters. Retrieved 2012-07-09. 
  3. ^ "Journal Citation Reports Contents -- Immediacy Index" ((online)). Thomson Reuters. Retrieved 2012-07-09. The Immediacy Index is 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.