Journal Citation Reports Journal Citation Reports: A .

Journal Citation ReportsJournal Citation Reports:A Primer on the JCR andJournal Impact FactorWeb of ScienceTrust the difference

2The Journal Citation Reports, first publishedin 1975, is an annual compendium of citationdata that provides a systematic and objectivemeans to assess influence and impact at thejournal and category levels. It contains reportson citation performance for science andsocial science journals and the relationshipsbetween citing and cited journals. Toreceive a Journal Impact Factor a journalmust be covered in the Science CitationIndex Expanded or Social Sciences CitationIndex of the Web of Science. Only journalscovered in these citation indexes are eligibleto appear in Journal Citation Reports (JCR)and receive a Journal Impact Factor (JIF).

Clarivate Analytics Journal Citation Reports: A Primeron the JCR and Journal Impact Factor3How is the JCR used?Journal Impact Factor NumeratorThe Journal Impact Factor was originally developed byDrs. Eugene Garfield and Irving H. Sher as a metricto aid in selection of additional journals for the newlycreated Science Citation Index. Today librarians continueto use the JCR as a tool in building and managing theirjournal collections. Publishers use the JCR to gaugejournal performance and assess their competitors.The numerator of the JIF consists of any citationto the journal as defined by the title of the journal,irrespective of what item in the journal might becited. Each cited reference in a scholarly publicationis an acknowledgement of influence. JCR thereforeaggregates all citations to a given journal in thenumerator regardless of cited document type.How is the Journal ImpactFactor calculated?The JIF is defined as citations to the journal in the JCRyear to items published in the previous two years, dividedby the total number of scholarly items, also known ascitable items, (these comprise articles and reviews)published in the journal in the previous two years.The citations that comprise the JIF numerator aredrawn from the journal and proceedings indexes inWeb of Science Core Collection (Science CitationIndex Expanded, Social Sciences Citation Index,Arts & Humanities Citation Index, Emerging SourcesCitation Index, and both the Science and SocialScience and Humanities editions of the ConferenceProceedings Citation Index). Citations from the BookCitation Index do not contribute toward JCR metrics.2015 Journal Impact Factor (2015 citations to items in 2014 2015citations to items in 2013) / (citable items in 2014 citable items in 2013).Source paper- publishedin 2015All previousyears201320142015Cited reference- published in2013 or 201420162015 citations captured from journals and proceedings inany/all items published to a journal in the 2013 and 2014NumeratorNumber of Articles and Reviews (citable items)published in the journal in 2013 and 2014Denominator2015 JIF

4Web of Science Trust the differenceJournal Impact Factor DenominatorJCR and Web of ScienceCitable items in JCR are defined as all materialsindexed in Web of Science as articles and reviewspapers. Items with any other document type, includingeditorial material, letter, and meeting abstract, arenot included in the denominator of the JIF.A key difference between Web of Science and JCR isthat Web of Science is continually updated, while the JCRdata represents a snapshot from a specific time, namely,the date when the data were extracted for analysis. Thisdifference reflects the essential nature of each product.Document types are assigned at the section level,and each journal is evaluated individually for thecharacteristics of the items in each section. In ourconsideration of the sections of a journal and whatdocument type they are to have upon indexing,we review the following elements that are typicalbibliographic characteristics of scholarly works: Web of Science is a vital and evolving record of thedynamic world of scholarly communication. New sourcematerial is added continually and new citations toolder records are continually included and indexed. Abstract Descriptive article titles Named author with author addresses Article length Cited References Data contentNo single feature defines a “citable” item – butconsideration of all of these, across many examples ofthe items in each section results in a strongly consistentassociation between items identified as “citable” (articlesand reviews) and items whose citations create the JIF. JCR, on the other hand, is a report on the citationimpact of a defined set of journals at a given moment intime. As a result, JCR provides insight into the citationperformance of each journal in a given year measuringimpact and influence in general as well as citationimpact in the well-defined context of each journal’ssubject category.Therefore, attempts to use Web of Science data toreplicate JCR metrics are not appropriate and will leadto results that may vary from those reported in JCR.The JCR also differs from Web of Science in thefollowing sense: If one piece of citation-related datachanges in a Web of Science article, only that onearticle and those to which it connects directly areaffected. More citations may link to that article, butthose citations were not linked anywhere else previously.If citation-related data changes for one journal in theJCR, all journals might be affected. For example, if theitem count changes for one journal, not only does thatchange the JIF for that journal, but also the medianand aggregate Impact Factors for any/all categories inwhich the journal appears. It will also affect the rank incategory for many or even all the journals in a category.Finally, the Article Influence metric for each journal isbased on item counts for every journal. Changing onejournal’s JIF denominator would require re-calculationof the Article Influence score for every journal inboth editions. JCR is a network of interconnecteddata, and if one piece of data changes, it changesthe overall network’s structure and morphology,sometimes drastically. It is for the aforementionedreasons that the JCR is reloaded only once per year,with all data updates occurring simultaneously.

Clarivate Analytics Journal Citation Reports: A Primeron the JCR and Journal Impact FactorHandling Journal Title Variationsin Cited ReferencesThere is great variation in how authors format citations,including how cited works (also known as source orjournal titles) appear in those citations. Handling thisissue is of critical importance for the JCR to properlyattribute and aggregate journal-level metrics. To managethese variants, JCR editors build a series of dictionaryentries associating each preferred title with a set ofvariant forms for the cited work. These entries arederived using direct observation and analysis of citedreference data. JCR editors have access to more than1 billion cited references in Web of Science as wellas to specialized citation reports that are preparedfor each JCR production cycle. Variants can includealternative abbreviated forms, alternate spellings,common misspellings or typographical errors, partnumbers, numbered supplements, and others. Anyobserved variant that can be associated unambiguouslywith the covered title is included in the dictionary.Timing of AppearanceJournals only appear in the JCR when there are threecomplete and known years of source data; this isalways and uniformly the case. This is because the JIF isdefined as citations in the JCR year to items publishedin the previous two years, divided by the total number ofscholarly items published in those previous two years.New journals, i.e., those starting from volume 1,issue 1, can be included in the JCR after their firstyear because their prior two years of source dataare known—as zero. Journals that have undergone atitle change are another instance of this exception.In both scenarios these journals would not receive aJIF, but are still listed in the JCR with other metricsto their credit,like the Immediacy Index, that can becalculated on the source data we have for that journal.5Title ChangesThere is a defined series of events that occur whena journal changes its title for the JCR production.The following scenario applies to a journal thatreleases with a new title in the year 2016. EditorialDevelopment evaluates all new titles for continuingcoverage. Assuming the new title is selected, thefollowing happens across the years 2015-2019.In 2015, Journal A publishes its last issue. Thefirst issue in 2016 is newly titled Journal B.When the year 2015 JCR is published in June of 2016,only Journal A will be listed (since there were neitherarticles nor citations for Journal B in the year before itsrelease). It will show all JCR data: Total Citations, JIF,Immediacy Index, source item counts, cited and citingjournal data, and cited and citing half-life calculations.When the year 2016 JCR is published, in June of 2017,Journal A will have a listing containing Total Citationsand an Impact Factor based on citations in 2016 tocontent in 2015 and 2014. It will also have cited journaldata and a cited half-life, but no other metrics areapplicable. Journal B will have a listing containing TotalCitations, Immediacy Index (based on citations in 2016to articles published in 2016), and source item counts.It will have citing journal data and a citing half-life.When the year 2017 JCR is published in June of 2018,Journal A will be listed with Total Citations and anJIF (based on Citations in 2017 to articles publishedin 2015 only). It will also have cited journal data anda cited half-life, but no other metrics. Journal B willhave a listing containing all citation data and metrics- however, the JIF will be based on citations in 2017to items published in 2016 only. The JIF for Journal Ain 2015 would be deceptively high, since it is basedon a section of the citation time-course that is higher,or even peaked. The JIF for Journal B, on the otherhand, will be deceptively low, since it is based oncitations to quite recent articles, before most journalsand subjects have fully developed citations. It is fairlysimple math to combine the two JIF to gauge the overallperformance of the title across the period of transition.Finally, in the year 2018 JCR, published in Juneof 2019, only Journal B will be listed - withcomplete citation data and metrics. All furtheryears, of course, will show only the new title.