Citation Rankings

What is Citation Analysis?

Citation analysis is a way of measuring the relative importance or impact of an author, an article or a publication by counting the number of times that author, article, or publication has been cited by other works.

Tools for Citation Analysis

There are several tools for performing citation analysis. The Argonne Research Library subscribes to the Web of Science platform of products, which gives us access to InCItes, Essential Science Indicators, and Journal Citation Reports. The tabs to the left will describe each of these tools in greater detail.

There are a number of different metrics used by the Web of Science citation ranking tools. Some of the more important ones are listed below.

H-Index

The h-index was developed by J.E. Hirsch, a physicist at the University of California, San Diego. You can view the original paper in which he first describes it here.

The h-index is based on the highest number of papers included that have had at least the same number of citations. The value of h is equal to the number of papers (N) in the list that have N or more citations.

Thus, if the h-index for an author is 10, it means that of all the author's published articles, at least 10 have been cited 10 or more times.

Journal Impact Factor

The journal impact factor measures the importance of a journal and "is a measure of the frequency with which the 'average article' in a journal has been cited in a particular year or period". The Impact Factor is calculated by dividing the number of citations in the current year by the total number of articles published in the two previous years. An Impact Factor of 1.0 means that, on average, the articles published within the last two years have been cited one time. An Impact Factor of 2.5 means that, on average, the articles published within the last two years have been cited two and a half times. Citing articles may be from the same journal; most citing articles are from different journals.

Average impact factors can vary widely across scientific disciplines, and so should only be used to compare journals within the same subject area.

Eigenfactor

The Eigenfactor score was developed by J. West and C. Bergstrom at the University of Washington. Journals are rated according to the number of citations from other journals. Self-citations are not included in the measurement. In addition, citations from highly ranked journals are assigned greater weight than citations from lower ranked journals. Eigenfactor scores scale with the total impact of a given journal, so that journals with greater impact on their field have higher scores.

Eigenfactor scores are calculated at eigenfactor.org, where they can be freely viewed.