1. Determine the statistical time range: Usually, the calculation of impact factors is based on the data of the last two years. For example, the impact factor of 20 19 is calculated based on the data of 20 17 and 20 18.
2. Obtain reference data: The calculation of impact factors requires a lot of reference data. These data usually come from special databases, such as WebofScience, Scopus and so on. These databases will record the publication year, author, journal and other information of each paper, as well as the number of times the paper was cited.
3. Calculate the total number of citations: For a journal, it is necessary to count the total number of citations of all papers published in the last two years. This includes direct reference and indirect reference.
4. Calculate the number of citable papers: the number of citable papers refers to the number of all papers published by this journal within the statistical time range. If a paper has been published before the statistical time range, but it is cited within the statistical time range, then this paper will also be counted as the number of citable papers.
5. Calculate the impact factor: the impact factor is equal to the total cited times divided by the number of citable papers. The impact factor is a logarithmic result, usually based on 10. For example, if the total number of citations of a journal is 1000 and the number of citable papers is 500, its impact factor is 2.0.
It should be noted that the impact factor is not the only criterion to measure the quality of academic journals, but only reflects the influence and academic value of journals. In addition, the influence factors of different disciplines may be very different, so these factors need to be considered when comparing the influence factors of different journals.