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What are impact metrics?
Impact metrics or publication metrics attempt to measure the quantitative impact of a journal article, a journal, or an individual author. It considers things such as citation counts, download counts, pageviews, and mentions, both within and outside of the academy.
This page contains information about the different types of metrics available, suggestions on where to look for impact metrics, and some notes about their benefits and limitations.
Why and how are impact metrics used?
Researchers may look at journal-level metrics when considering where to publish their work. For more information on selecting a journal for publication, see Publishing Choices.
Article-level, author-level, and Altmetrics can be used to indicate a researcher's contribution to their field. When reviewing a researcher's work, it’s not always possible to read everything to which that person has contributed. Impact metrics provide an indicator of the attention or volume of interest about an author’s work that may be used to inform decision making. Impact metrics are not intended to replace fulsome review.
Due to the limitations mentioned below, some researchers making significant contributions may be underrepresented by impact metrics. These metrics should therefore be used with caution and always in tandem with other strategies for assessing researchers and their work.
What are the limitations of impact metrics?
Impact metrics are not standard in every field. They focus on academic literature, and are underrepresented in other types of scholarly work.
Some limitations of impact metrics include:
- Recent articles, newer journals, and researchers who are at an earlier stage of their career or who publish in languages other than English may be underrepresented by impact metrics.
- Publishing frequency and types (ex. books vs. journal articles) vary from one field to another, precluding comparisons across different subject areas.
- Authors who frequently cite their own work manipulate impact metrics and make them less reliable.
- Impact metrics focus on the volume or attention received rather than the quality of research.
- Having a large number of citations is not necessarily a marker of merit, as articles may be cited for negative reasons.
The impact of an individual research article is most commonly measured using citation counts which calculate the number of times the article has been cited in other research. Many databases, and a number of software applications, track these metrics. Citation counts for a particular article can vary from one source to another, depending on the number and type of sources indexed per database.
Researchers sometimes use article-level metrics to discover interdisciplinary research opportunities by looking at who is citing and using their research from other disciplines.
Where can I find citation counts?
Many databases provide citation counts. Look for "Times Cited" "Cited by" "Citations" or "Metrics."
Web of Science
Includes 8500 international journals in the sciences, social sciences, and arts and humanities. Click on "Times Cited" to see the articles that cited the source.
Google Scholar enables you to search specifically for scholarly literature, including peer-reviewed papers, theses, books, preprints, abstracts and technical reports from all broad areas of research. Click on "Cited by [#]" to see articles that cited the source.
Multidisciplinary, Open Access journal. In addition to providing citation counts, each source listed in the search results has number of views, number of bookmarks, and number of shares in social media, making PLOS an option for Altmetrics as well as citation counts. Learn more about PLOS article-level metrics.
In addition to the examples above, many EBSCO databases contain citation counts, including Business Source Complete, PsycINFO, and Academic Search Premier. Learn more about finding citation counts in EBSCO databases.
What are the benefits of Altmetrics?
- Attempt to measure impact outside the academy.
- Provide a more immediate measure of impact; citation counts and h-index can take years to accumulate.
- Measure the impact of non-traditional publications, like datasets and code.
- Can provide the context and reasons for a citation.
Where can I find Altmetrics?
Note: The following resources are subscription-based, and SFU Library does not currently subscribe to these services.
Offers a free bookmarklet and other paid services that provide article-level metrics derived from social media sites, newspapers, government policy documents, and other sources.
An open-source tool that allows authors to create an impact profile using metrics derived from social media sites and traditional citations. These metrics can also be applied to non-traditional publications, such as blog posts, data sets, and software.
Plum Analytics tracks more than 20 different types of artifacts, including journal articles, books, videos, presentations, conference proceedings, datasets, source code, and cases to help researchers measure their scholarly impact.
Author-level metrics are commonly calculated using a citation index which considers the amount of research an author has published in addition to the amount that their research has been cited in other research. Different resources use various methods for calculating a citation index; for example, some adjust the score to reflect self-citations, while others (such as the h-index) do not.
While the h-index is the most common, other citation indexes which you may encounter include:
- Egghe's g-index
- Google Scholar i10-index
- Zhang's e-index
Make sure you have a researcher profile when checking your author-level metrics, since the citation index score will be invalid if more than one researcher has the same name.
Where can I find author-level metrics such as the h-index?
An author's research impact is commonly measured using a calculation called the Hirsch Index, or h-index. The h-index looks at both the number of articles an author has published and the number of citations for each article. An author with an h-index of 12 has at least 12 papers that have each been cited 12 times.
Resources that calculate citation indexes
Journal-level metrics are one factor to consider when choosing a suitable publishing platform for your research. Visit our Publishing Choices page for more details on factors to consider when choosing a journal.
The impact of an individual journal is usually measured by looking at the average number of citations received by published articles in the journal. It attempts to measure a journal's relative importance as it compares to other journals in the same field. There are different methods for calculating a journal's impact: some give more weight to citations from other influential journals, and some exclude self-citations from the article's author, while others do not.
It’s important to keep in mind that most journal impact metrics privilege established journals and penalize newer ones, regardless of the respective journals’ calibre. Reviewing a prospective journal’s impact is only one aspect of choosing where to publish.
Where can I find journal-level metrics?
Journal Citation Reports (JCR)
Covers 7000+ peer-reviewed journals in approximately 200 disciplines. Journals can be sorted by impact factor, immediacy index, total cites, total articles, cited half-life, or journal title. JCR uses a method called the Journal Impact Factor to calculate a journal's impact, as follows:
Additionally, JCR can be used to calculate a journal's Eigenfactor and Article Influence Score.
- The Eigenfactor ranks a journal based on the number of citations its articles receive, weighting citations that come from other influential journals more heavily. A benefit of the Eigenfactor over the JIF is that it excludes self-citations.
- The Article Influence Score is the Eigenfactor divided by the number of articles in the journal. This metric is most directly comparable to the Journal Impact Factor.
These rankings can also be found at Eigenfactor.org
Search for CiteScore, SJR and SNIP metrics, or download them in an Excel file.
- CiteScore is calculated by the total number of documents (including letters and editorials) published in a journal in the last three years, divided by the total number of citations to those documents.
- SCImago Journal Rank (SJR) accounts for the number of citations received by a journal and the importance of the journal it came from. This metric is based on the idea that "all citations are not created equal." You can also find SJR metrics at SCImago Journal & Country Rank.
- Source Normalized Impact per Paper (SNIP) is the ratio of a journal's citation count/paper and the citation potential in its subject field. Citation potential takes into consideration the citation norms based on subject area and journal type.
Google Scholar Metrics
In addition to measuring an author's impact, the h-index calculated by Google Scholar can also measure the impact of journals. To get started, browse the top 100 publications (available in several languages), ordered by their five-year h-index and h-median metrics. To see which articles in a publication were cited the most and who cited them, click on its h-index number to view the articles as well as the citations underlying the metrics.
Harzing Journal Quality List
A collation of business and economics journal rankings from a variety of sources, sorted by title, subject area or ISSN. Rankings are updated a few times a year.