Since the Institute for Scientific Information (ISI) first published SCI and SSCI in 1961, the two databases have grown to include a good number of academic journals that are both international in scope and comprehensive in subject representation. However, it should be noted that the results of NTU Ranking may favor universities with better performances in sciences and social sciences, and under-represent performances in arts and humanities research. The database Arts & Humanities Citation Index (A&HCI) mainly indexes English-language journals, while arts and humanities researchers’ publications take various forms (such as books) in their native languages.


Therefore, this ranking system does not include the A&HCI database because it may fail to objectively and accurately represent the research performances of arts and humanities researchers. Focusing on the data obtained from SCI and SSCI allows fairer comparisons on universities around the world. The indicators used in this ranking system have the following three characteristics:



1. Emphasize the quality of research - the indicators assessing research quality (research impact and research excellence) account for 75% of the performance score.



Research impact and research excellence evaluate the quality of a university’s research output. The calculation of each university’s score is based on the number of citations to its published articles, h-index of the last 2 years, number of Highly Cited Papers, and number of articles published in high-impact journals (Hi-Impact journal articles). These indicators will be explained further in the Indicators section.



2. Neutralize biases caused by university size or the faculty numbers.



Traditionally, the size of a university affects its ranking when the number of articles is used as the sole indicator for research output. Because the number of articles is closely tied to the number of faculty members, rankings employing number of articles often favor larger universities. This ranking system corrects that flaw by incorporating the average number of citations in the last 11 years and h-index of the last 2 years in the calculation of the universities’ performance scores (explained below).The inclusion of indicators that evaluate short-term performances corrects the flaws.



To further show the possible influences of university size on ranking, in addition to the original ranking, this ranking system also provides an adjusted ranking based on university size. Four indicators significantly affected by university size are normalized by each university’s number of full-time faculty; these include the number of articles in the last 11 years, number of articles in the current year, number of citations in the last 11 years, and the number of citations in the last 2 years. This ranking system employs faculty numbers obtained from the following sources (listed by priority in usage): numbers of full-time faculty obtained from university websites, numbers of faculty registered at each country’s higher education administration, and numbers of faculty/staff obtained from university websites.



3. Take into account a university’s short-term research performance (constituting 50% of the score), which ensures a more objective comparison between universities with histories of varying lengths.



The indicators used in this ranking system seek to represent both the long-term and short-term research performances of a university. The inclusion of indicators evaluating short-term performances corrects the flaws resulted from not differentiating indicators that favor universities with longer histories. These short-term performance indicators include: the number of articles in the current year, the number of citations in the last 2 years, h-index in the last 2 years, and number of articles in the current year in high-impact journals.



Through the use of these indicators, this ranking system attempts to objectively compare the research performance and achievement of universities worldwide. The relative strengths and weaknesses of a university as revealed in the ranking provide insights into higher education administration and resource allocation.