This chart shows the 2-Year Impact (article-only) of Expert Opinion on Orphan Drugs over time and its percentile among journals. Only research articles are counted in both the numerator (citations) and denominator (citable items).
The 2-year article impact for year X equals the citations received in year X to research articles published in years X-1 and X-2, divided by the number of research articles published in those two years. Unlike the standard 2-year impact, only items classified as research articles are counted in both the numerator and denominator.
