Impact Factor
Journal Impact Factor
The journal Impact Factor is the average number of times articles from the journal published in the past two years have been cited in the JCR year.
The Impact Factor is calculated by dividing the number of citations in the JCR 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 one or two year ago have been cited one time. An Impact Factor of 2.5 means that, on average, the articles published one or two year ago have been cited two and a half times. The citing works may be articles published in the same journal. However, most citing works are from different journals, proceedings, or books indexed by Web of Science.
5-Year Journal Impact Factor
The 5-year journal Impact Factor is the average number of times articles from the journal published in the past five years have been cited in the JCR year. It is caclulated by dividing the number of citations in the JCR year by the total number of articles published in the five previous years.
The 5-year Impact Factor is available only in JCR 2007 and subsequent years. You may calculate the 5-year Impact Factor using an earlier JCR year as a starting point by following these instructions.
Aggregate Impact Factor
The aggregate Impact Factor for a subject category is calculated the same way as the Impact Factor for a journal, but it takes into account the number of citations to all journals in the category and the number of articles from all journals in the category. An aggregate Impact Factor of 1.0 means that that, on average, the articles in the subject category published one or two years ago have been cited one time. The median Impact Factor is the median value of all journal Impact Factors in the subject category.
The Impact Factor mitigates the importance of absolute citation frequencies. It tends to discount the advantage of large journals over small journals because large journals produce a larger body of citable literature. For the same reason, it tends to discount the advantage of frequently issued journals over less frequently issued ones and of older journals over newer ones. Because the journal impact factor offsets the advantages of size and age, it is a valuable tool for journal evaluation.
Impact Factor Trend Graph
The Impact Factor Trend Graph shows the Impact Factor for a five-year period. To view the graph, click the Impact Factor Trend button at the top of the Journal page.
Impact Factor Box Plot
The Impact Factor Box Plot depicts the distribution of Impact Factors for all journals in the category. More information.
Journal h-index is one measure of the quality of a journal and can be calculated using data from Web of Science, Scopus or Google Scholar. As with the impact factor, journal h-index does not take into account differing citation practices of fields (unlike the weighted SJR and SNIP) and so is best used to compare journals within a field.
The h-index, or Hirsch index, measures the impact of a particular scientist rather than a journal. "It is defined as the highest number of publications of a scientist that received h or more citations each while the other publications have not more than h citations each." 1 For example, a scholar with an h-index of 5 had published 5 papers, each of which has been cited by others at least 5 times. See instructions below for finding the h-index using Web of Science, Scopus and Publish or Perish, which is downloadable from Harzing.com.
Note that an individual's h-index may be very different in different databases. This is because the databases index different journals and cover different years. For instance, Scopus only considers work from 1996 or later, while the Web of Science calculates an h-index using all years that an institution has subscribed to. (So a Web of Science h-index might look different when searched through different institutions.)
Journal Citation Reports® offers a systematic, objective means to critically evaluate the world's leading journals, with quantifiable, statistical information based on citation data.
By compiling articles' cited references, JCR helps to measure research influence and impact at the journal and category levels, and shows the relationship between citing and cited journals. Available in Science and Social Sciences editions. You can search do your journal citation report search here