Sample Selection

Pre-Analysis Institution Screening
 
The selection of universities in this ranking system was modified in the year of 2021. The selection was based on the outstandingly performed universities that were announced by each of the following ranking programs, with an inclusion of World university rankings and 27 subjects . Ranking programs used as references included the 2020 NTU Rankings, ARWU, QS ,THE, and U.S. News. In the end, 1,417 universities were selected, with 800 universities’ ranking being issued.
 
Prior to the modification in 2021, 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 1,200 institutions based on the institutions’ number of published journal articles and number of citations. Non-university institutions were then removed from the list, followed by the project staff comparing the remaining universities to those included in the other ranking programs such as ARWU, THE, QS and U.S. News. Data used to assess the performances of the universities was drawn from Clarivate’ s ESI and Web of Science Core Collection (WOS), which included SCI and SSCI, and Journal Citation Reports (JCR).
 
 
Authority Control
 
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. This ranking system also considered the merging and splitting of universities (or different campuses in a university system) and included publications by university-affiliated institutions such as research centers and university hospitals. This effort ensured the accuracy of each university’s number of published journal articles and the subsequent citation statistics.
 
This ranking system addressed the flaw caused by the classification of institution in ESI. 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 name of the university system. 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 rectified this flaw by manually searching SCI/SSCI and to identify the actual number of articles produced by the individual campuses, as well as the citations of those articles. 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 campuses.