Impact factors

Journal impact factors

The journal impact factor is a statistical measure used to rank and evaluate journals.

The impact factor is the average number of times articles - that is, research articles, technical notes and reviews - from the journal published in the last two years have been cited in the current year. When used as a point of comparison with other journals, the impact factor indicates the relative importance of a journal within a given field.

As a general guideline, impact factors may be of interest to academic and research staff when selecting journals for publishing their work.

The journal impact factor is currently calculated by Thomson ISI for more than 7000 journals contained in its citation indexes (science, technology, social sciences) and published in:

Journal citation reports

show the most frequently cited journals in a field

highest impact journals in a field

leading journals in a field

related journals in a field

citation characteristics for a subject category

includes Eigenfactor metrics (Eigenfactor Score & Article Influence Score)

and is updated annually

Note that not all journals are covered by Thomson ISI citation indexes and therefore do not have calculated impact factors.

To determine whether the journal is peer-reviewed or refereed, see the guide on Publishing in quality journals.

Citation supplier for ERA

Scopus will be the citation data supplier for Cluster One - Physical, Chemical and Earth Sciences (PCE) in the ERA initiative. For further information, see the University's web page on Indicators.

ERA journal rankings

For journal rankings used in the Excellence in Research Australia (ERA) initiative, see the University's web page on Journal Rankings.

Other impact factors

h-index or Hirsch index

The h-index was developed in 2005 by Jorge Hirsch to qualify the impact and quantity of individual scientist's research output. The h-index serves as an alternative to more traditional journal impact factor metrics.

The measure is simple: a scientist with an h-index of, say, 20 has published 20 articles that have each attracted at least 20 citations. This means that the rest of the author's papers have less than 20 citations. The index works properly only for comparing scientists working in the same field as citation conventions differ widely among different fields.

How to calculate your h-index:

The h-index can be manually determined using an Internet database such as Google Scholar. Licensed resources such as Scopus and the Web of Science provide automated calculators. Note that each database is likely to produce a different h for the same scholar, because of the different coverage in each database.