Sample Selection

Sample Selection

This ranking system employs bibliometric methods to analyze and rank the scientific paper performances of the world’s top 800 universities. The selection of the 800 universities for inclusion in this ranking system was based on information obtained from the Essential Science Indicators (ESI). Of more than 4,000 research institutions listed in ESI, this ranking system first selected the top 900 institutions based on the numbers of published journal articles and numbers of citations. Non-university institutions were then removed from the list, and the project staff compared the remaining universities to those included in other ranking programs such as ARWU, THE, QS, and U.S. News. Data used to assess the performances of the universities was drawn from ISI’s ESI and Web of Science Core Collection (WOS), which includes SCI and SSCI, and Journal Citation Reports (JCR).
 
The concept of authority control was employed to retrieve data indexed under different forms of a university’s name in the aforementioned databases – i.e. the official name, the abbreviated name and other possible forms of the name. Given the merging and splitting of universities (or different campuses in a university system), this ranking system also included publications of university-affiliated institutions such as research centers and university hospitals. This effort ensured the accuracy of the number of published journal articles and the subsequent citation statistics of each university.
 
Some university systems have several campuses. A few campuses within a particular university system may have been commonly perceived as individual institutions. However, they are indexed in ESI only by the university system name. For example, the University of Connecticut system includes the main campus in Storrs and five regional campuses throughout the state. Furthermore, it also contains the Schools of Medicine and Dental Medicine at UConn Health in Farmington. These are all indexed under “University of Connecticut” in ESI.
 
This ranking system corrected this flaw by manually searching SCI/SSCI to identify the actual number of articles and citations of these articles produced by the individual campus. Likewise, this ranking system employed the same manual searching procedures to ensure that the measurement of each university’s Highly Cited Papers fairly represented the research performance of the individual campus.