Journal Citation Reports is a resource released annually, containing metrics that help you understand the citation patterns of published literature. One such metric is the Immediacy Index, which allows you to see how quickly the average article published in a particular journal is cited relative to others in its subject category. This can be useful in helping you identify which journals are publishing the “hottest” papers in a discipline– papers that get cited almost immediately after they’re published. To calculate a journal’s immediacy index, we first aggregate all of the article-level Web of Science Core Collection citation data for the journal. Using data from the current year only of the JCR edition, we calculate immediacy index by dividing the total number of citations to items published in the journal by the number of articles and reviews it published during that same year. For this example, I’ll look at Chemical Engineering journals in the current JCR year, sorted by Immediacy Index. Energy & Environmental Science has the highest score. Let’s take a closer look at this journal’s record. Energy & Environmental Science has an immediacy index of 6.751 for 2016. If I click directly on the linked number, I can view the calculation of this score. Immediacy Index is calculated by dividing the number of citations accrued during the current JCR year to items published in the journal in the same year, by the number of articles & reviews the journal published in that year. The resulting quotient represents the average number of times an article in this journal was cited in the same year it is published. This indicates how quickly on average articles in a journal are cited. Energy & Environmental Science published 325 articles & reviews in 2016 that were cited 2,194 times that same year. So the average article published in 2016 in Energy & Environmental Science was cited 6 times in that same year. One thing to keep in mind when considering immediacy index scores is the timing of a journal’s publication schedule. An article published in a journal early in the year has a better chance of being cited than one published later in the year– for example, an article published in January 2014 has more time to be cited by other material published in 2014 than an article published at the end of year, in December. For this reason, many journals that publish infrequently, or only once late in the year, have low immediacy index scores. Publication information for a journal can be found on the top of a profile page. For more information on JCR metrics, please consult the JCR help file.