The JCR Notices file (available to JCR subscribers here) is a quick way to inform customers of journals that will show new or changed metrics when the JCR data are reloaded in late summer. The journals that require updates come from one of two sources: Identification of a needed correction; or completion of missing content needed for the calculation of metrics.
Corrections:
Most inquiries to Customer Technical Support or the JCR production team can be answered with an explanation of the content or derivation of the JCR data. However, sometimes customer questions surface potential problems with the metrics for a journal. When this occurs, these issues are investigated and any anomalies in the JCR published data are corrected. These can be found in the updated metrics posted to the JCR Web Notices file each week.
Corrections fall into one of three categories, which are identified in the Notices file by the column “Reason for Update”:
- Did not appear – identifies a journal that was incorrectly excluded from appearing in the JCR. This could be the result of an unrecognized title change or volume 1 coverage decision that caused an apparent gap the receipt of older issues. Correction will result in the journal having a full record in the JCR reload, containing all metrics that can be calculated. To date, 9% of the JCR updates are journals that did not appear in the JCR June release.
- Citations – identifies a journal with some irregularity in citation count. Sometimes a small change in the way a title is presented in the journal can result in authors citing the title differently, and our analysis may not have taken this new variant into account. Alternatively, we may identify a previously unseen title that is cited equivalently and have to update citations to one or both “homograph” titles. (See also: Understanding the Journal Impact Factor) Citation type corrections may result in the citation count – and the associated citation metrics – either increasing or decreasing. To date, 11% of JCR updates are Citation type.
- Item count – identifies a journal where too many or too few of the published items were identified as “citable.” The citable item count changes will affect either the Immediacy Index or both the Journal Impact Factor and the 5-year Impact Factor. (See also: Understanding the Journal Impact Factor) Depending on the nature of the correction, the metrics may increase or decrease. To date, 11% of JCR updates are Item count type.
Missing issue(s):
During each year’s JCR production, Editors examine journals that show a significant year-to-year change in the number of published citable items, or that have unexplained gaps in content. Most of the journals reviewed in this step have year to year variation that is a result of a normal variation in content, such as a change in publication frequency, the release of a supplemental or expanded special issue, or a simple change in page count. A decrease in item count could be the result of publishing one or more “combined” issues, or an overall drop in the page count per issue. Alternatively, a decrease in item count could indicate that one or more issues was not successfully receipted and indexed for Web of Science.
If our research determines one or more issues are missing that would affect the Journal Impact Factor denominator, the journal is flagged by the JCR editors as being ineligible for inclusion in the JCR since insufficient data would result in an incorrect Journal Impact Factor. We provide our Publisher Relationsgroup with the details of the missing issue(s). Publisher Relations will then arrange for the delivery and indexing of the missing content. This year, Thomson Reuters Publisher Relations pursued over 870 issues that prevented nearly 150 journals from appearing in the JCR in June. Their efforts, and the speedy response of publishers and editors to their requests, resulted in over 100 journals now prepared for the JCR reload. Indexing of this previously missing content allows the JCR to calculate a complete and accurate Journal Impact Factor.
The 2010 JCR data will be reloaded by the end of September. All the JCR data will be updated to reflect the new content. Although the Journal Impact Factor of any one journal will have not alter the Journal Impact Factor of any other journal, the change to the JCR content will have several broader effects. Some journals’ rank in category may change by one or more metrics as any category that contains an updated journal will also show updated aggregate category metrics. Because the Eigenfactor metrics (Eigenfactor Score and Article Influence Score) are based on the content and structure of the JCR citation network as a whole, change to an individual journal’s citation or item count has the potential to affect every other journal in the network. All Eigenfactor metrics will be re-calculated based on the expanded citation network.
The completed JCR re-load will be available in the next 1-2 weeks. Release of the new data will be announced on this site.
The stability of the JCR metrics is very important to all our users. Accuracy and responsiveness to changes in our database are equally important. We continuously strive to provide the most comprehensive, reliable metrics to our customers to help them understand a journal’s true place in the world of scholarly literature.
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September 28, 2011 - Update: The JCR 2010 data reload is complete. All changes are fully incorporated in the product and the list in the Notices file is removed.
