The University Libraries has recently acquired internet access to the Institute for Scientific Information's (ISI's) Journal citation reports (JCR). Internet access, which begins with 2000 data, will greatly improve the availability and usefulness of this important resource. You can find Journal citation reports online at http://purl.lib.uiowa.edu/jcr.
For additional details about JCR see the information below, adapted from ISI's web site, or see the "Information for New Users" at the web site.
Edward Shreeves
Director, Collections and Information Resources
August 21, 2001
Journal Citation Reports is a comprehensive and unique resource for journal evaluation, using citation data drawn from over 8,400 scholarly and technical journals worldwide. Coverage is both multidisciplinary and international, and incorporates journals from over 3,000 publishers in 60 nations.
The JCR is the only source of citation data on journals, and includes virtually all specialties in the areas of science, technology, and social sciences. The JCR can show you the:
JCR Web shows the relationship between citing and cited journals in a clear, easy-to-use framework. JCR Web is available annually in two editions:
Each annual database contains the citation data from the JCR year indicated. For every journal covered, the following information is collected or calculated:
ISI does not recommend that JCR users depend solely on citation data in their journal evaluations. Citation data are not meant to replace informed peer review. Additionally, careful attention should be paid to the many conditions that can influence citation rates, such as language, journal history and format, publication schedule, and subject specialty. The number of articles given for journals listed in the JCR include only original research and review articles. Editorials, letters, news items, and meeting abstracts are not included in article counts because they are not generally cited. Journals publishing in non-English languages or using non-Roman alphabets may be less accessible to researchers worldwide, which can influence their citation patterns. This should be taken into account in any comparative journal citation analysis.
You should also consider the following four conditions, which may affect journal's ranking and impact factor:
Impact factor by article type. ISI manually codes each published article, but it is not feasible to individually code the millions of references processed each year. Therefore, citation counts in the JCR do not distinguish between citations to letters, reviews, or original research articles, even though article counts in the JCR include only original research and review articles. If a journal publishes a large number of letters one year, there may be a temporary increase in the number of citations received. This increase will not be proportionately reflected in the JCR article count given. To identify and evaluate any such phenomena, detailed article-by-article analyses can be conducted.
Changes in journal format. Sudden changes in a journal's size can affect the impact factor. The average number of cites per article is lowered when there are more one-year-old articles than two-year-old articles, because article citation rates tend to peak in the second year after publication. Likewise, when an article count drops, the impact factor may rise temporarily. The article counts used to calculate the impact factor are provided, so that any sudden changes can be noted.
Title changes and impact factor. In the first year after a title change, the new title is listed without an impact factor, because the article count for the two preceding years used in impact factor calculations is zero. The superseded title is listed with a normal impact factor. One year later, the JCR lists separate impact factors for the new title and for the superseded title. In this second year, the impact factor for a new title may be lower than expected, because the article count includes only younger articles. Similarly, the impact factor for the superseded title may be higher than expected because it is based upon only older articles. To calculate a unified impact factor, the user can total the cites to the two previous years and divide that by the sum of the article counts for the two titles. For a listing of journal title changes, where both the new title and the superseded title appear in the JCR, see the Journal Title Changes page, which is accessible from the Journal Search page and the Summary List page.
Cited-only journals in the JCR. Some of the journals listed in the JCR are not citing journals, but are cited-only journals. This is significant when comparing journals, because self-citations from cited-only journals are not included in the JCR data. Often, self-citations represent a significant percent of the citations that a journal receives. The cited-only journals may be ceased or suspended journals, or superseded titles. Any journal that has no Citing Journal page information is a cited-only journal. Evaluations including cited-only journals are enhanced by self-citation analysis.
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