If it is the influencing factor, K is a certain year, Nk- 1+Nk-2 is the number of papers published in the previous year or two, and Nk- 1 and Nk-2 are journals cited for several years.
Take the calculation of IF in 20 19 as an example: if 2019 = (citation times in 2018+citation times in 2017)/(number of articles in 2018+20/kloc-)
The impact factor, abbreviated as IF, is the data in the Journal Citation Report (JCR) produced by Thomson Reuters. That is, the total number of cited papers published by a journal in the first two years of the reporting year (JCR year) divided by the total number of papers published by the journal in these two years.
This is an internationally accepted periodical evaluation index. The impact factor has become a general index of periodical evaluation in the world. It is not only an index to measure the usefulness and exhibition of periodicals, but also an important index to measure the academic level of periodicals and even the quality of papers. The influence factor is a relative statistic.
Importance of influencing factors:
Impact factors are not the most objective criteria for evaluating the influence of periodicals. Generally speaking, the higher the impact factor, the greater the influence of the journal. For some comprehensive or important research fields, the citation rate is relatively high because of the wide range of research fields. For example, biological and chemical journals are generally more likely to have higher influence.
Although the impact factor can represent the academic quality to some extent, there is no linear proportional relationship between the impact factor and the academic quality. For example, it cannot be said that a journal with an impact factor of 5.0 is necessarily better than a journal with an impact factor of 2.0, and the impact factor does not have the function of accurately and quantitatively evaluating academic quality.
Some domestic scientific research institutions often use the number of cumulative impact factors or single impact factors as quantitative standards when evaluating scientific research performance. Some researchers may not be promoted or rewarded because of the difference of influence factors of 0. 1, which is absolutely undesirable.