JCR (full name: periodical citation report) is a periodical citation report published annually by Thomson Reuters (now renamed Keruiweian) Company. JCR is a unique multi-disciplinary periodical evaluation tool. By indexing and counting the references, the influence of a research can be measured at the periodical level, and the relationship between cited and cited periodicals can be displayed.
JCR includes two editions: the scientific edition and the social science edition. JCR-Science covers more than 8,500 periodicals, covering 176 disciplines. JCR- Social Science covers more than 3,000 periodicals and 56 disciplines.
JCR counts and calculates citation and cited data of journals, and defines impact factors and other indicators for each journal to report. The two most concerned data in JCR data are: journal impact factor and JCR partition.
Impact factor (IF): An impact factor is a quantitative index representing the influence of a periodical. The impact factor of a periodical refers to the average number of citations in the previous two years. Impact factor IF = the number of citations of papers published in the first two years of a journal in that year/the total number of papers published in the first two years of the journal.
JCR Zoning: Because it is difficult to compare and evaluate journals among different disciplines, Thomson Reuters divides SCI and s SCI journals into four grades according to the year and discipline, and each discipline classification is divided into four zones, namely Q 1, Q2, Q3 and Q4, according to the impact factor of journals in that year, Q1>: Q2 > Q3 & gtQ4 (q: quarter in category), so as to distinguish the influence of journals in different disciplines, that is, the journal ranking in JCR report (JCR partition).