Later today (June 18, 2015), the 2014 edition of the Journal Citation Report (JCR) will be released, listing citation performance metrics for 11,149 journals. While the JCR calculates many different citation-based metrics, most editors and publishers will be chiefly interested in just one single metric–the Journal Impact Factor (JIF).
The JIF measures, for any given year, the citation performance of journal articles in their second and third year of publication. Despite regular attacks on the use of this metric for evaluation purposes (viz. DORA), JIFs are considered a crucial factor for where scientists choose to submit their manuscripts. A high initial JIF can result in a flood of new manuscripts (e.g. PLOS ONE); conversely, a steady JIF decline can signal that scientists should submit their best papers elsewhere. For new journals without a JIF, encouraging submissions can be a real challenge.
This year, 272 journals will receive their first Impact Factor. The JCR will also suppress 39 titles –29 for high rates of self-citation and 10 for “citation stacking,” a behavior that resembles a citation cartel. Suppression from the JCR lasts one year and requires reevaluation before a journal is relisted. Fifty-three percent of journals will receive an increase in their Impact Factor from last year.
While most editors and publishers will be primarily interested in their Journal Impact Factor, the JCR includes other citation-based metrics: an Impact Factor based on a five-year observation window, the Citing and Cited Half-Life, and two network based metrics–Eigenfactor and Article Influence Score–both of which weight citations based on the importance of journals within the citation network.
This year, the JCR is adding two complementary calculations so that journals can be compared within and between subject disciplines. The JIF Percentile simply translates a journal’s category rank into a percentile. For example, a journal that is ranked 19 out of 291 Biochemistry & Molecular Biology journals would receive a JIF Percentile score of 0.94. Curiously, using the JCR normalization method,* a journal ranked first among seven Andrology journals would only receive a score of 0.93.
The second new metric, Normalized Eigenfactor (NE) Score converts a journal’s Eigenfactor into a multiplicative score centered around 1, such that, if a journal received an NE score of 2, it would be twice as influential as the average journal in the network. It should be noted that Eigen-based metrics (unlike the Impact Factor) require iterative computation upon the entire citation dataset, and there is no standard for how that calculation is done. Scopus, a competing citation dataset produced by Elsevier, has developed its own calculation methods that some believe are superior to the JCR.
Thomson Reuters has made several improvements to its InCites interface, which debuted last year and has been the target of complaints by both new and regular users. The JCR visualization–an interactive widget that seems to serve little function other than to titillate the bored and bewilder the perplexed–is now hidden by default. The interface now permits a user to download the data behind many of their tables and charts, and the company is also in the process of expanding its advisory group to help with future usability issues.
In sum, this year’s release illustrates some practical and useful improvements and a growing willingness to listen to the feedback from their stakeholders.
* JIF Percentile is calculated as (n – r + .5)/n where n = number of journals in the category and r = descending rank of the journal within that category.