JCR & SNIP

Journal Citation Reports® is a factual database issued every year by Thomson Reuters from the USA. It contains records with impact factor data for the most important serials produced all over the world. This data has been available in the COBISS system since 1994. Source Normalized Impact per Paper (SNIP) is a database published twice a year by the Leiden University's Centre for Science & Technology Studies (CWTS) in cooperation with Elsevier. It includes records with citation impact data (impact factor data) of scientific serials covered by the Scopus database from 1999 onwards.

Within COBISS, the JCR and SNIP databases fall into two main groups: Science Edition (SE), which contains data from journals in the field of science and technology, and Social Science Edition (SSE), which contains data from journals in the field of sociology and humanities. Both are available in COBISS+ via the link Impact factor for journals.

As the data on journal impact factor is calculated on the basis of publications from previous years, the data for the current year can only be published subsequently. Data for the previous year is normally published in the summer months (e.g. in the summer of 2014, journal impact factor data for 2013 are published). The JCR database will be updated with the journal impact factor data only for the previous year (e.g. in 2014 for 2013), then it will be updated again at the end of the year when minor corrections (errata) will be published for the previously published year. The SNIP database will be updated with the journal impact factor for the previous year (e.g. in 2014 for 2013), and at the same time, data for the previous years will be updated. The database is updated again in the spring months when modifications for the previous years are published.

In the report, for an individual publication from a journal that has an impact factor, a data from the JCR/SNIP databases will be considered for the year of publication (e.g. for publications from 2010, data for the journal in JCR/SNIP from 2010 will be considered). There are two exceptions. The first exceptions are publications published this year or previous year when (until new data is acquired) a data for the last serial from the JCR/SNIP will be considered (e.g. for publications from 2013 and 2014, until impact factor data for 2013 is obtained, a data for the journal in the JCR/SNIP databases from 2012 will be considered; when the impact factor data for the year 2013 is obtained, publications from 2013 and 2014 will consider a data for the journal in the JCR/SNIP databases from 2013). The second exceptions are publications published in the last two years before the journal was granted its first impact factor. If a journal received its first impact factor in 2010, a data for the journal in the JCR/SNIP databases for 2010 will be considered also for publications published in 2008 and 2009.

From the JCR or SNIP database, data on categories (fields of research) are displayed on the basis of the publication year, quartiles of the IF distribution the journals occupy for a scientific field and the data on above-average scientific excellence in the last 5 years are displayed from The list of foreign databases.

For reports by journals, summary data from the JCR or SNIP database for all publications included in the input time period are displayed for an individual journal, in accordance with the abovementioned rules and exceptions that apply when taking into account years from an individual database. If the input time period is before 1992 for JCR or before 1997 for SNIP, the data on journals that include those publications will not be displayed. Similar applies when no publication is included in a report for an individual journal since 1992 for the WoS database or since 1997 for the Scopus database.

JCR SNIP