The impact factor (IF) normally is calculated by Thomson Reuters based on the Web of Science (WOS). However, Google Scholar now provides an alternative Google-based impact factor. Google Scholar is the only openly available database suitable for journal metric calculation. It has a wide coverage and is a meaningful source. For this reason, Today Science is calculating its own Impact Factor by applying Thomson Reuters'(TR) algorithm based on Google Scholar's citation counts. The 2014 impact factor of a journal would be calculated as follows:
- A = total cites in 2016 = 20 (final data was got in December, 2016)
- B = 2016 cites to articles published in 2014 - 2015 = 20 (this is a subset of A)
- C = number of articles published in 2014 - 2015 = 13
- Google-based impact factor (2 years) for 2016 = B/C (TR algorithm)= 20/13 = 1.54 (final IF was updated in January 2017)
An impact factors for 2016 can only be published once this year is over (in 2017). A Google-based impact factor has never a fixed value. Today science will provide updates of the IF during the year.