Impact Metrics and Scholarly Attribution

SCImago Journal and Country Rank, or 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 journals where such citations come from.

The SJR indicator, which is inspired by the Google PageRank algorithm, was developed for extremely large and heterogeneous journal citation networks. It is a size-independent indicator and it ranks journals by their ‘average prestige per article’ and can be used for journal comparisons in science evaluation processes.

SJR calculation uses data provided by Scopus.

Google Scholar Metrics uses the H-Index formula to rank journals. The Metrics Home Page lists the top 100 h5-index ranked publications in English.

"The h5-index is the h-index for articles published in the last 5 complete years. It is the largest number h such that h articles published in 2010-2014 have at least h citations."

Because disciplines have varying publishing models and expectations, comparing journal citation indices across research areas is not recommended. However, Google Scholar Metrics also provides h5-index ranked lists by subject area. Researchers can select language, discipline category, and, if desired, a subject sub-category.

By clicking on the h5-index for each journal, one can access the references for the most cited articles and the number of times each article was cited within that 5-year period.

Clicking on the Cited by number within each reference provides a list of those articles.

Clicking on an article name can lead to a source and sometimes full text. 

Caveat: Google Scholar Metrics is limited to articles indexed in Google Scholar, a database that does not have set journal inclusion parameters. For best results, multiple sources and methods should be used in identifying the most significant journals and articles in a research area.

The Eigenfactor™ Score uses a network of citation data to assess the relative importance of journals in the science and social science communities. Journals with many citations from influential journals are rated as influential themselves.

The Article Influence™ Score determines the average influence of a journal's articles.

Score calculation is based on the citations received over a five year period, but it also considers which journals have contributed these citations so that highly cited journals will influence the network more than lesser cited journals. References from one article in a journal to another article from the same journal are removed, so that Eigenfactor Scores are not influenced by journal self-citation.

Since the number and frequency of citations vary by discipline, the Eigenfactor algorithm adjusts for these differences.

In addition to articles from scholarly journals, Eigenfactor also includes newspaper articles, theses, popular magazines and other items in its reference material.

Web of Science's Journal Citation Reports offers a means to statistically compare and evaluate some of the world's leading journals.

• Delivers quantifiable statistical information based on citation data. 
• Provides a variety of impact and influence metrics, including the Journal Impact Factor and Eigenfactor®
• Includes rank-in-category tables, journal self-citations, and Impact Factor boxplots

JCR provides comparison data for how journals rank among other titles in a subject category and by citation value and impact factor. One can also retrieve historical trend data for several years to see the direction of the impact. However a specific article can trigger a measurement that is a one-time spike.

Using JCR

Go to Journal Citation Reports.

You can search for a specific journal or you can scroll down and browse a full list of Journals, or search by Categories, Publishers, or Countries/Regions.

If you'd like to review journal rankings in your field, you can try searching by Categories. Searching by Categories provides an opportunity to choose from a long list of fields. Selecting "Environment/Ecology" reveals provides 13 additional categories and 1,753 journals. 

I can click into these categories further, and I'll see a list of journals. 

Here, I can sort by journal impact factor (JIF), total citations, and more, such as what percentage of the articles are Open Access (OA). 

Clicking on a journal's name gives more specific information about that journal.

If I scroll down further, I'll see more information about the journal’s performance and the information about the journal's impact factor.

Scrolling down reveals much, much more information and graphs, including Journal Citation Indicator (JCI), Total Citations, Citation distribution, ranks, content metrics, additional metrics, and much more.

Information such as this can help you see how a journal's impact factor has changed over time. Comparisons with other journals might indicate rising or decreasing influence. However, due to differences in databases and algorithms, more than one type of ranking index should be consulted in the overall analysis of a journal's significance in a field. 

By studying journal impact metrics, such as those presented in this database, scholarly researchers and academic organizations can make better informed decisions about the importance of the journals they purchase and publish in.

Caveat: JCR metrics are limited to articles indexed in Web of Science. For best results, multiple sources and methods should be used in identifying the most significant journals and articles in a research area.