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Bibliometric measures

The most commonly used metrics used to measure the impact of research outputs and publications are listed below. [Please note that many other metrics are available and can be used in different databases]

Scholarly output

The total number of outputs published. It measures productivity rather than impact.

Citation counts

The number of citations received. It measures citations for individual outputs or a set of outputs.


The productivity and impact of a researcher's outputs. It is based on the number of publications as well as the number of citations they have received.

An author has an H-index of n if they have published n papers, each of which has been cited at least n times.

Example: to have an H-index of 15, 15 of your papers must have been cited at least 15 times each.

Watch a video on finding citation counts and H index in Web of Science

Field-weighted citation impact (only available in SciVal)

The ratio of citations received, relative to the expected world average for the subject field, publication type and publication year.

Outputs in top percentiles (only available in SciVal)

The number or percentage of outputs in the top most-cited publications in the world/UK/specific country.

Journal impact factor (only available in Journal Citation Reports)

The importance of a particular journal. It is based on the average number of citations received per paper published in that journal in the preceding 2 years.

Watch a video on how to use Journal Citation Reports

SCImago journal rank

The importance of a particular journal. It is an alternative to the Journal Impact Factor. The SCImago Journal Rank places higher value/weight to citations from more prestigious journals.

The SCImago Journal and Country rank is a portal that includes the journals and country scientific indicators developed from the information contained in the Scopus database. This indicator shows the visibility of the journals contained in the Scopus database from 1996.

Scopus SNIP (only available in Scopus)

The importance of a particular journal. The Scopus Snip normalises for citation rate subject differences. It is a ratio of a journal's citation count per paper and the citation potential in its subject field.


Altmetrics are based on the number of times an article is shared, downloaded or mentioned on social media, blogs or newspapers.

Find out more about altmetrics