91吃瓜

The 5 year journal impact factor is the average number of times, the articles published in a journal get cited in last 5 years. It is calculated by dividing the number of citations received with the total number of articles published in previous five years. The 5 year journal impact factor is available only for the journals that completed 5 or more volumes.

The aggregate journal impact factor for a subject category is calculated using the same method as the journal impact factor for a journal, but it also includes the number of citations for all journals in the category and the number of articles from all journals in the category. An aggregate journal impact factor of 1.0 implies that the articles in the subject category published in recent two years have been cited once on an average. The median Impact factor is the median value of all journals impact factors in the subject category. The journal impact factor extenuates the significance of absolute citation frequencies. It alleviates the advantage of large journals over small journals because large journals circulate a larger body of citable literature. It also mitigates the benefit of frequently issued journals over less frequently issued ones and of older journals over newer ones. For the reason that the journal impact factor offsets the advantages of size and age and it is a helpful contrivance for journal evaluation.

*2017 Journal Impact Factor was established by dividing the number of articles published in 2015 and 2016 with the number of times they are cited in 2017 based on Google Scholar Citation Index database. If 'X' is the total number of articles published in 2015 and 2016, and 'Y' is the number of times these articles were cited in indexed journals during 2017 then, journal impact factor = Y/X