Terminology

Citation

A measure of impact.

Self-citation

When an author cites a work s⁄he has co-authored. Bibliometric analyses often choose not to include self-citations.

Citation window

The time period used in a citation analysis. Often a two year interval, e.g. for an article published in 2004, citations from 2005 and 2006 are counted.

Normalisation

Comparing like with like. Field normalisation, for example, means that the number of citations received by an author for articles within a certain discipline are compared with the world average (usually the Web of Science average) for that discipline. A score of >1.0 means the author has a citation per paper score better than the world average.

Fractionalisation

Dividing up the number of citations received by a paper by the number of authors. This can also be done according to the number of institutions, countries and so on in the author address fields.

Indicators

Bibliometrics uses a number of indicators to analyse publications and authors.

Examples of indicators:

Crown indicator

A field normalised mean. The number of citations received during a defined period of time divided by the world average for the same discipline, same time period and same type of publication. The world average = 1.0.

Hirsch index (h-index)

An author′s h-index is the number of publications (h) by the author which have been cited at least h number of times. E.g. if an author has published 53 articles, of which 15 have been cited 15 or more times, that author′s h-index is 15.

Top 5%

The proportion of publications which are amongst the 5% most cited publications in that subject area over a defined period of time.