The impact factor is a measure of journal quality. It depends upon the frequency with which an article receives citations. It is the most important metric while evaluating the work of a researcher for funding & research positions. The quality of the researcher’s work is judged by the number of articles published and the impact factor of the publishing journal.
JCR-Journal Citation Report
Impact factors of the Journals are published every September in Journal Citation Reports (JCR). It is an annual publication by Clarivate Analytics, a Philadelphia and London based organization. JCR is based on citations compiled from SCI (science citation index) and SSCI (social science citation index). It monitors and excludes journals that exhibit anomalous citation behavior such as self-citation and citation stacking. JCR 2020 includes a total of 12,171 journals in 83 countries with 236 research categories.
How to calculate the impact factor
Journal Impact factors have a year census period and have two year’s target window. Suppose that in a journal ABC, a total of articles published in the year 2017 is 240 and a total number of articles published in the year 2018 240. So the total number of articles published in two consecutive years 2017 and 2018 is 240+240=480. Now suppose that articles published in the year 2017 & 2018 were cited 600 times in the year 2019. So impact factor for the journal for the year 2019 is the ratio of a number of citations in 2019 by the articles published in 2017 & 2018 to the number of articles published in 2017 & 2018 and is 600/480=1.25. Hence impact factor of the journal in the year 2019 is 1.25.
While calculating the Impact factor, the numerator includes all the items in the journal i.e. articles, letters, abstracts whereas the denominator includes only the published articles. Impact factor calculation does not include books and book chapters.
|Journal Impact Factor|
Criticism against Impact factor
The use of impact factor in analyzing the work of a researcher faces many criticisms:
- Scientific fields to which the journals belong influences the impact factor significantly. For instance, in biomedical fields, a long reference list with more than 50 items is nothing new. On the other hand, in Mathematics literature, the number of references remains even lower than 20. These cultural differences lead to substantial deviation in impact factors across fields.
- Scientific journals rank higher than clinical journals in terms of impact factor. This is because scientific journals tend to cite only scientific articles while clinical journals cite both scientific and clinical articles.
- Some journals resort to the malignant practice of self-citation to increase their IF. They ask the authors to cite the reference of their own journal to increase IF.
- Errors, misprints, and inconsistencies in citations distort the impact factor. Misprints in the list of references may affect up to one-quarter of references.
- Journal that publishes more review articles have greater IFs than the others. Review articles receive more citations than other formats. This way they increase the IF of the journals.
And many other factors distort the impact factor. Thus we can say that the impact factor should not be the only parameter to judge the quality of a publication or the work of a researcher.