The Leiden Ranking 2011/2012: Data collection, indicators, and interpretation

The Leiden Ranking 2011/2012 is a ranking of universities based on bibliometric indicators of publication output, citation impact, and scientific collaboration. The ranking includes 500 major universities from 41 different countries. This paper provides an extensive discussion of the Leiden Ranking 2011/2012. The ranking is compared with other global university rankings, in particular the Academic Ranking of World Universities (commonly known as the Shanghai Ranking) and the Times Higher Education World University Rankings. Also, a detailed description is offered of the data collection methodology of the Leiden Ranking 2011/2012 and of the indicators used in the ranking. Various innovations in the Leiden Ranking 2011/2012 are presented. These innovations include (1) an indicator based on counting a university's highly cited publications, (2) indicators based on fractional rather than full counting of collaborative publications, (3) the possibility of excluding non-English language publications, and (4) the use of stability intervals. Finally, some comments are made on the interpretation of the ranking, and a number of limitations of the ranking are pointed out

Excellence with leadership: the crown indicator of SCImago Institutions Rankings Iber report

Although there are many models for ranking higher education institutions, the SCImago Institutions Rankings  methodology stands out for its ability to present quantitative and qualitative indicators of scientific output. Besides Total number of published papers, several indicators are concerned with quality dimensions of published papers, such as International collaboration, Scientific leadership or High quality publications . However, official rankings are provided solely on the basis of one indicator: Output (total number of published papers ). This paper presents a statistical I-distance method that integrates all the indicators into one value, which therefore represent a rank and show which of the input indicators is the most important for the process of ranking. Our results clearly showed that Excellence with Leadership  occupies the most significant spot

How to improve the prediction based on citation impact percentiles for years shortly after the publication date?

The findings of Bornmann, Leydesdorff, and Wang (in press) revealed that the consideration of journal impact improves the prediction of long-term citation impact. This paper further explores the possibility of improving citation impact measurements on the base of a short citation window by the consideration of journal impact and other variables, such as the number of authors, the number of cited references, and the number of pages. The dataset contains 475,391 journal papers published in 1980 and indexed in Web of Science (WoS, Thomson Reuters), and all annual citation counts (from 1980 to 2010) for these papers. As an indicator of citation impact, we used percentiles of citations calculated using the approach of Hazen (1914). Our results show that citation impact measurement can really be improved: If factors generally influencing citation impact are considered in the statistical analysis, the explained variance in the long-term citation impact can be much increased. However, this increase is only visible when using the years shortly after publication but not when using later years.Comment: Accepted for publication in the Journal of Informetrics. arXiv admin note: text overlap with arXiv:1306.445