Embedded Files
Measuring Impact
Measuring Impact
Impact measurement is a controversial topic as there are no agreed standards. Criticisms include metric maximising practices, diverting attention away from actual content, and ignoring the reasons for citations. Various initiatives such as the San Francisco Declaration on Research Assessment (DORA) and Leiden Manifesto aim to educate and address these pitfalls.
Nevertheless, metrics can be useful tools for research assessment when applied appropriately. The following explains some of the traditional ways of measuring impact:
Journal Impact
Journal Impact
Journal metrics rate the importance of a journal based on the number of articles published and the number of citations received. One aim is to help researchers decide which journal to publish in. Each system has its strengths and weaknesses and so judgment must be exercised when interpreting and applying the figures. Common journal metrics includes:
Journal Impact Factor (JIF)
Published annually in Web of Science's InCites Journal Citation Reports, JIF measures how frequently an "average article" is cited over a defined period and is thus an indication of how often a journal is cited by other journals in a field. Surprsingly, the calculation is rather simple, based over 3 years:
SCImago Journal Rank (SJR)
Based on Scopus data, SJR was inspired by Google's PageRank algorithm and has visual presentation capabilities. It is a free online tool that ranks publications by weighted citation per document. A citation from an important journal will count as more than one and likewise, those in a less prestigious journal will have a lower weight.
Source Normalized Impact per Paper (SNIP)
Scopus-based SNIP measures contextual citation impact to allow direct comparisons between subject fields. For example, due to the usual higher value for STEM-related journals, Arts and Humanities journal titles are given a higher rating to balance out the value difference.
CiteScore
Freely accessible via Elsevier's Journal Metrics, CiteScore is based on citations received in one year to articles published in the previous 3 years, divided by the number of articles indexed in Scopus published in the same 3 years.
You may find Professor Anne-Wil Harzing's Where to submit your paper? Compare journals by impact helpful when trying to decide where to publish.
Author Impact
Author impact metrics are based on the number of publications by an author and the number of times they have been cited. Key author impact measurements include:
h-index
h-index
The h-index attempts to balance scholarly productivity with citation impact. A scholar with an index of h has published h papers that have been cited by other papers at least h times. Thus an author with an h-index of 50 has published 50 articles each with 50 or more citations. It is sometimes seen as unfair to early-career researchers.
i10-index
i10-index
Used only in Google Scholar in its My Citations feature, i10-index is a basic and straightforward way of measuring a scholar's productivity. It simply counts only the number of publications with at least 10 citations.
Article Impact
Article metrics are from a variety of different data sources, such as the traditional Citation Counts, Field-Weighted Citation Impact (FWCI), and the more recent altmetrics. Scopus, Web of Science and Google Scholars all provide easy ways for authors to find their article impact.
Citation Counts
The assumption of Citation Count is that the more important or influential the work, the higher the number of Citation Count. However, the argument is that citations don't measure quality and are purely based on subjective judgment. Citation Counts also favour mainstream research and may reveal negative instead of positive attention.
Field-Weighted Citation Impact (FWCI)
Field-Weighted Citation Impact metrics are a useful benchmark regardless of the differences across disciplines. Sourced from SciVal, FWCI compares the number of citations received by a researcher against the average number of citations received by all other publications that have the same publication year, type and discipline, calculated as follows:
FIELD-WEIGHTED CITATION IMPACT =
Number of citations received by an article
--------------------------------------------------------------------------------------------------------------------
Expected number of citations for similar articles
1.00 means article was cited at world average for similar publications
1.45 means article was cited 44% more than expected
0.75 means article was cited 25% less than average
In addition to the above, altmetrics have become increasingly popular as measures of article level impact in recent years. See the next section for more details.
Why Altmetrics?
Why Altmetrics?
Short for alternative metrics, altmetrics complement traditional impact measures but unlike citation counts which may take years to emerge, they are available almost immediately. The birth of altmetrics in recent years has been a benefit to many scholars, in particular, those from Humanities and Social Sciences, providing them with an alternative way to assess their work apart from traditional journal metrics. Altmetrics have gained widespread attention, giving researchers total new perspectives to see how their works are influencing not only scholarly communities, but also beyond.
Altmetrics are still in their infancy. Just like traditional metrics, they have limitations and can also be easily manipulated. To learn more, visit: altmetrics.org.
Altmetrics
Examples of altmetrics include: mainstream media coverage, citations on Wikipedia, discussions on research blogs, mentions on Facebook or Twitter, or exports to citation management systems like Mendeley. Main ways to access and make use of altmetrics data include:
Found on the right hand sidebar of the Scopus Document details page, the 5 categories of PlumX metrics track various altmetrics data. This has become the primary source of article level metrics on Scopus alongside citation count and field-weighted citation impact.
Funded by the National Science Foundation and the Alfred P. Sloan Foundation, ImpactStory allows users to create profiles that gather usage data from various online research sharing platforms.
Not to be confused with altmetrics.org, altmetric.com is a product offered by Digital Science that uses a doughnut symbol to visualise the reach and impact of articles. altmetric.com widgets can be found on many publisher article metrics pages or repositories such as Figshare.
Page updated
Report abuse
This site uses cookies from Google to deliver its services and to analyze traffic. Information about your use of this site is shared with Google. By using this site, you agree to its use of cookies.
Learn more
Got it