How is the 2-year impact calculated for universities?
The university's 2-year impact for year X equals the citations received in year X to items affiliated with Leiden University and published in years X-1 and X-2, divided by the number of citable items from those two years. This follows the same formula as journal 2-Year Impacts but is computed independently from citation and affiliation data, it has no connection to journal 2-Year Impacts and does not reflect the 2-Year Impacts of the journals in which Leiden University's work appeared.
