Metrics and Impact for PBRF

Information about the types of metrics and impact measures that can be used in PBRF evidence portfolios

Author level metrics

The PBRF focuses on your research outputs from 2012-2018. You can provide author level metrics in your PBRF Evidence Portfolio in the Platform of Research Contextual Summary in the Supporting Information section or to provide information about other prestigious co-authors on your work.

H-index is one of the most well-known author level metrics. 

The formula states: "A scientist has index h if h of his or her Np papers have at least h citations each and the other (Np-h) papers have ≥h citations each" (Hirsch, 2005).

For example, if you've published 2 papers, and each paper has been cited 2 times, you will have a h-index of 2.

Thus the h-index attempts to measure the impact of your output - you need to have published a large number of papers, which were in turn cited a large number of times, to have a high h-index.

For more on the advantages and disadvantages of this metric, see this blog post by Library Connect entitled Talking to your researchers about the h-index.

i10-index  a variation on the H-index from Google Scholar that reflects the number of your publications with at least 10 citations.

Article level metrics

Article/item level metrics can be used in the NRO and Research Contribution portions of the Evidence Portfolio.

Metrics in this area may include:

Citation count - total count of citations the output has received. This metric will vary between the database you source them from (Google Scholar would usually provide the highest citation count).


Field-weighted citation impact (FWCI) - shows how well cited this article is when compared to similar articles. A FWCI greater than 1.00 means the article is cited more than expected according to the average. It takes into account: The year of publication, Document type, and the disciplines associated with its source. The FWCI is the ratio of the article's citations to the average number of citations received by all similar articles over a three-year window. 

Citation Benchmarking - shows how citations received by this article compare with the average for similar articles. The 99th percentile is high, and indicates an article in the top 1% globally. It takes into account: date of publication, document type, and disciplines associated with its source.


Category-normalized citation impact (CNCI) calculated by dividing the actual count of citing items by the expected citation rate for documents with the same document type, year of publication and subject area. When a document is assigned to more than one subject area an average of the ratios of the actual to expected citations is used. The CNCI of a set of documents, for example the collected works of an individual, institution or country, is the average of the CNCI values for all the documents in the set.

Percentile in Subject Area - The percentile in which the paper ranks in its category, document type and database year, based on total citations received by the paper. The higher the number of citations, the smaller the percentile number. The maximum percentile value is 100, indicating 0 citations received.


Journal level metrics

Journal metrics measure the influence and research impact of journals. The measures are based predominately on citation counts. Journal metrics are used by researchers to identify the most appropriate and influential journals in which to publish and to track citation patterns to make strategic and funding decisions. Journal level metrics can be used to show that you have published in or acted as a reviewer or editor for prestigious or highly regarded journals. These can be mentioned in NRO descriptions and/or Research Contributions.

There are three main sources for finding journal metrics. Journal Citation Reports (JCR), Scopus Compare Sources and Google Scholar Metrics.


Journal Impact Factor (JIF) - the average number of times articles from the journal published in the past two years have been cited in the current Journal Citation Report year. Citations to articles from the most recent two full years, divided by the total number of articles from the most recent two full years.

Eigenfactor - a measure of a journal's importance. The Eigenfactor rates journals according to the number of incoming citations, with citations from highly ranked journals weighted to make a larger contribution to the Eigenfactor than those from poorly ranked journals. 


CiteScore -  is calculated by dividing the number of citations a journal title receives in one year by the number of documents indexed in the previous three year period. As opposed to JIF, this metric includes all document types in a journal. 

SCImago Journal Rank (SJR) - a journal influence metric whereby a journal’s subject field, quality and reputation have a direct effect upon the value of the citations it gives to other journals. SJR is a measure of scientific influence of scholarly journals that accounts for both the number of citations received by a journal and the importance or prestige of the source journals.

Source Normalized Impact per Publication (SNIP) - The ratio of the journal’s citation count per paper and the citation potential in its subject field. The impact of a single citation is given higher value in subject areas where citations are less likely, and vice versa. SNIP measures contextual citation impact by weighting citations based on the total number of citations in a subject field.

Google Scholar

h5-index  - the largest number h such that at least h articles that were published in the last five complete calendar years in that publication were cited at least h times each. For example, a publication with five articles cited by, respectively, 17, 9, 6, 3, and 2, has the h-index of 3.

h5-median - is the median of the citation counts that were published in the last five complete calendar years in its h-core (a set of top cited h articles from the publication). For example, the h-median of the publication above is 9. The h-median is a measure of the distribution of citations to the articles in the h-core.

Traditional metrics tools

Citation metrics are based on the number of times a work is cited as a indicator of the quality of the work: the more citations, the greater the impact.

Citation data are available from the following citation databases.

Database Content and Coverage

Metrics available for PBRF

Web of Science

Science Citation Index (1900-present),  Social Sciences Citation Index (1900-present), and the Arts & Humanities Citation Index (1975-present).

Citation Count




InCites is a web-based research evaluation tool based on citation data from Web of Science content. 


Citation Count

Percentile in Subject Area

Category-normalized citation count

Journal Impact Factor




The Scopus Journals title list contains over 34,000 titles in total. The Scopus Books title list contains more than 116,000 books.

Citation coverage available from 1970-present


Citation Count

Field-weighted citation impact

Citation Benchmarking




SciVal SciVal is a subscription based research performance assessment tool which uses data from Scopus. It provides more advanced metrics than those available in Scopus only and also allows you to benchmark individual researchers, groups of researchers and institutions based on a variety of different metrics.


Citation Count

Field-weighted citation impact



Metrics cards

Google Scholar 

Coverage: Unknown

Provides information about who is citing your publications and graphs of citations to your work over time, not limited to a specific database. 


H-index (current and since 2012)

Citation count


Note that citation metrics are only as good as the citation data indexed in each resource. No citation database indexes all published works, and no citation database covers all subject areas equally. Please contact your Subject Librarian for advice about where to start, or using any of these tools.