Library Help: Office For Open Research

What are citations? 

A citation refers to the acknowledgment of one research work by another, typically through referencing it in a publication. Citations are often used to track the impact and influence of research within the academic community, serving as a key metric for evaluating the relevance, quality, and reach of scholarly work. 

Simple citation counts for articles and authors 

Citation counts are a basic metric that indicate how many times a publication or an author's body of work has been referenced by other scholarly works. These counts can be found in several platforms including: 

• Scopus: Elsevier's abstract and citation database: 

• Web of Science (WoS): Clarivate's citation index 

• OpenAlex: An open-source scholarly database 

• Scite: A research and analysis discovery platform 

It is important to note that citation counts may vary across these platforms due to differences in coverage. Factors affecting these differences include: 

• The range of journals and publications indexed 

• The types of outputs included (e.g., articles, conference proceedings, books) 

• The time frame of coverage 

When using citation counts, we recommend that you consider checking multiple sources for a more comprehensive view of a publication's or author's impact. Please see our guidance on responsible use of metrics for more information.

Normalisation and Field-Weighted Citation Impact (FWCI) 

Raw citation counts can be misleading when comparing across different fields or time periods. In the Natural Sciences for example, typical citation rates can be up six times greater than in the Humanities. This is where the use of normalisation and field-weighting measures can be useful.  This is where the use of normalisation and field-weighting measures can be useful.

Normalisation is the process of adjusting citation counts to account for differences across fields, publication types, or time periods, allowing for fair comparisons between research outputs. One example of normalization is Elsevier's Field-Weighted Citation Impact (FWCI), which compares the actual number of citations a paper receives to the average number of citations expected for similar publications in the same field, year, and document type.  
 
A detailed introduction to these concepts is available within our My Research Essentials suite of online resources. 

This resource begins by explaining what a citation is, and why it is not always true that the more citations a publication receives, the more influential it is. The resource also demonstrates how average levels of citation can vary depending on the academic discipline in question, and how percentiles can be used to assess the citation impact of a publication. 

• My Research Essentials: Using citation analysis to measure research impact 

Field-Weighted Citation Impact (FWCI) 

FWCI is a potentially useful citation based metric available within Elsevier's SciVal platform. It can be particularly useful when analysing large groups of researchers and/or publications. FWCI: 

• Normalises citations based on the expected number of citations for publications of similar type, publication year, and subject field 

• Allows for fairer comparisons across different research areas and time periods 

• Is expressed as a ratio, where 1.00 represents world average performance 

Benefits of FWCI: 

• Useful for comparing research performance of groups such as universities or faculties 

• It can help in benchmarking against global or institutional averages 

• It provides additional context to raw citation counts 

Potential risks: 
As with any metric FWCI should always be used with caution. Please see our guidance on responsible use of metrics for more information. As a general rule:

• FWCI should not be used as the sole measure of research impact 

• For small groups or individual researchers, FWCI can be volatile, and so should be avoided 

• This metric may not fully capture the impact of highly interdisciplinary research 

• As citations emerge over time, recent publications may not have had enough time to accumulate meaningful citation data 

Elsevier has produced a more detailed guide to their FWCI metric, which includes specific guidance on how this metric is calculated: 

• Elsevier guide to Field-Weighted Citation Impact (FWCI) 

Percentiles in Citation Analysis 

Percentiles offer another way to contextualise citation performance. In SciVal, publications are ranked against others in the same field and with similar publication dates. 

Understanding Percentile Ranges 

• 99th percentile: Top 1% most cited 

• 95th percentile: Top 5% most cited 

• 90th percentile: Top 10% most cited 

• 75th percentile: Top 25% most cited 

• 50th percentile: Median 

When percentiles are useful: 

1. Institutional benchmarking: To compare the proportion of highly-cited papers across institutions 

2. Identifying top-performing research: This metric can be useful to identify standout publications within a large dataset 

Considerations when using percentiles: 

• Like FWCI, percentiles are field-normalised, allowing for cross-disciplinary comparisons 

• They are less affected by outliers than mean-based metrics 

• For recent publications, percentiles may change rapidly as citations accumulate 

• Very small fields or niche research areas may not provide reliable percentile data 

Elsevier has produced detailed guidance to their percentile-based metrics, which includes detailed guidance on how this metric is calculated: 

• Elsevier guide to outputs in top percentiles 

Further information and support 

When using any of the metrics detailed above, it is crucial to remember that they are tools to support evaluation, and not definitive measures of research quality or impact. They should always be used in conjunction with other forms of assessment, including peer review and qualitative evaluation. 

If you would like to discuss these metrics in further detail, and how you can access them, please contact us