Leiden ranking of scientific impact places UMass Amherst at No. 42 worldwide

The Center for Science and Technology Studies (CWTS) at Leiden University, The Netherlands, recently ranked the University of Massachusetts Amherst 42nd in the world, just after University College London, and 35th in North America in its Leiden Ranking for 2013, based on the science publication performance of 500 major universities worldwide. The ranking, an “advanced indicator of scientific impact” covers five areas: biomedical and health sciences, life and earth sciences, mathematics and computer science, natural sciences and engineering, and social sciences and humanities.
 
“Using a sophisticated set of bibliometric indicators, the ranking aims to provide highly accurate measurements of the scientific impact of universities and of universities’ involvement in scientific collaboration,” the compilers say. They used the Thomson Reuters’ Web of Science database in the period 2008-2011, including documents categorized as “article” or “review” but excluding books, conference proceedings and publications in journals not indexed there.Author self-citations are also excluded.
 
“Although the ranking is limited to universities, it does include organizations directly related to universities, in particular hospitals associated with universities.” However, the University of Massachusetts Medical School is ranked separately from UMass Amherst. CWTS compilers explain that publications are assigned to universities on the basis of author affiliations as indicated in those publications.
 
The Leiden Ranking counted three indicators of a university’s scientific impact to the end of 2012. First, compilers calculate the average number of citations of each university’s publications (mean citation score). Second, they identify the mean score normalized for field differences and publication year (mean normalized citation score). Here, a value of two means the university’s publications were cited twice above world average, for example. And third, they calculate the proportion of a university’s publications that belong in the top 10 percent most frequently cited (PP top10%) compared with other publications in the same field in the same year. The compilers regard this last measure as more stable than the mean normalized citation score and therefore the most important indicator for ranking.
 
UMass Amherst’s PP top 10 percent ranking is 15.4 percent compared to 25 percent for the world’s top-ranked university, the Massachusetts Institute of Technology. The campus is part of a cluster of institutions with PP top 10 percent rankings ranging from Emory University at 15.1 percent and Dartmouth College at 15.3 percent, for example, to the University of Michigan at 15.7 percent and the University of North Carolina Chapel Hill at 15.9 percent.