Ton van Raan

Leiden University | LEI · Center for Science and Technology Studies

We make an attempt to increase our understanding of the urban scaling phenomenon. To this end we simulate a city by a set of publications where the publications take the role of the city inhabitants and the terms in the publications represent all kinds of abilities and qualities of the inhabitants. We use scientific publications in a physics journa...

Urban scaling, the superlinear increase of socio-economic measures with increasing population, is a well-researched phenomenon. This article is focused on socio-economic performance scaling, which could possibly be driven by increasing returns of the size and density of interaction networks. If this is indeed the case, we should also find that spat...

A much debated topic is the role of universities in the prosperity of cities and regions. Two major problems arise. First, what is a reliable measurement of prosperity; second, what are the characteristics, particularly research performance of a university that matter? We focus on the research question: Is there a significant relation between havin...

Urban scaling, the superlinear increase of social and economic measures with increasing population, is an ubiquitous and well-researched phenomenon. This article is focused on socio-economic performance scaling, which could possibly be driven by increasing returns of the spatial size and density of interaction networks. If this is indeed the case,...

We investigated the role of universities in the prosperity of cities and regions. Performance characteristics of universities are derived from the Leiden Ranking 2020. The socioeconomic strength of a city is determined with the urban scaling methodology. Our study shows a significant relation between the presence of a university in a city and its s...

In this study we focus on characteristics of SBs that have not or hardly been investigated previously. We find that the choice of the awakening period in the selection of SBs has consequences for the measured citation patterns. Focusing on medical SBs we analyze patterns in the time-development of the citation impact of SBs; the influence of self-c...

We investigate socio-economic urban scaling behavior of municipalities in Denmark, the Netherlands, and in particular in Germany. Our interest is twofold. First we investigate whether, and to what extent, scaling occurs in various types of urban areas. The second important topic of research concerns the comparison of specific types of urban areas w...

We investigate publications in medical research that have gone unnoticed for a number of years after being published and then suddenly become cited to a significant degree. Such publications are called Sleeping Beauties (SBs). This study focuses on SBs that are cited in patents. We find that the increasing trend of the relative number of SBs comes...

We investigate Sleeping Beauties (SBs) in medical research with a special focus on SBs cited in patents. We find that the increasing trend of the relative number of SBs comes to an end around 1998. However, still a constant fraction of publications becomes an SB. Many SBs become highly cited publications, they even belong to the top-10 to 20% most...

We investigate the socioeconomic urban scaling behavior in Denmark, Germany, and the Netherlands. In the case of Denmark we examine the scaling of larger cities, municipalities within the Copenhagen agglomeration, and municipalities in rural areas. We also distinguish between municipalities with high and low centrality. Superlinear scaling of the g...

In this paper we investigate recent Sleeping Beauties cited in patents (SB-SNPRs). We find that the increasing trend of the relative number of SBs stopped around 1998. Moreover, we find that the time lag between the publication year of the SB-SNPRs and their first citation in a patent is becoming shorter in recent years. Our observations also sugge...

A Sleeping Beauty in Science is a publication that goes unnoticed (sleeps) for a long time and then, almost suddenly, attracts a lot of attention (is awakened by a prince). In our foregoing study we found that roughly half of the Sleeping Beauties are application-oriented and thus are potential Sleeping Innovations. In this paper we investigate a n...

Rapidly growing cities: as an example the scaling of the gross urban product (GUP) of Almere (city/municipality, blue diamonds) with the number of inhabitants. (TIFF)

Slowly growing cities: as an example the scaling of the gross urban product (GUP) of Eindhoven (city/municipality, blue diamonds; urban area, red squares) with the number of inhabitants. (TIFF)

Dataset of cities. (XLSX)

Time-dependent analysis. (DOCX)

A 'Sleeping Beauty in Science' is a publication that goes unnoticed ('sleeps') for a long time and then, almost suddenly, attracts a lot of attention ('is awakened by a prince'). The aim of this paper is to present a general methodology to investigate (1) important properties of Sleeping Beauties such as the time-dependent distribution, author char...

We investigated the socioeconomic scaling behavior of cities in the Netherlands and found significant nonlinear correlations between gross urban product as well as number of jobs with population size. This nonlinearity manifested by a super-linear power law scaling is found for both the cities defined as municipalities and for the agglomerations of...

A 'Sleeping Beauty in Science' is a publication that goes unnoticed ('sleeps') for a long time and then, almost suddenly, attracts a lot of attention ('is awakened by a prince'). In this paper we investigate important properties of Sleeping Beauties, particularly to find out to what extent Sleeping Beauties are application-oriented and thus are pot...

We investigated the socioeconomic scaling behavior of cities in the Netherlands and found significant nonlinear correlations between gross urban product as well as number of jobs with population size. This nonlinearity manifested by a super-linear power law scaling is found for both the cities defined as municipalities and for the agglomerations of...

We have developed and tested an evidence-based method for early-stage identification of scientific discoveries. Scholarly publications are analyzed to track and trace breakthrough processes as well as their impact on world science. The focus in this study is on the incremental discovery of the ubiquitin-mediated proteolytic system in the late 1970s...

Advanced bibliometric analysis is a powerful method to, first, assess with citation analysis the international influence of scientific work in a reliable, transparent and objective way, particularly in the natural science and medical fields, and in several of the engineering and social science fields; and secondly, discover with science maps patter...

We investigate the extent to which advances in the health and life sciences (HLS) are dependent on research in the engineering and physical sciences (EPS), particularly physics, chemistry, mathematics, and engineering. The analysis combines two different bibliometric approaches. The first approach to analyze the 'EPS-HLS interface' is based on term...

The quantitative study of science before the Science Citation Index; The Science Citation Index revolutionized the study of science; The take-off run to CWTS; Life at the forefront; CWTS in a changing world.

In this study an analysis of the effects of the different types of durability on the bibliometric performance at the group level is presented. The scientific production during the period of 1991–2000 of a set of 158 Dutch research groups in chemistry is studied considering several bibliometric indicators in the perspective of the durability of the...

Citation analysis has become an important tool for research performance assessment in the medical sciences. However, different areas of medical research may have considerably different citation practices, even within the same medical field. Because of this, it is unclear to what extent citation-based bibliometric indicators allow for valid comparis...

Recent studies of urban scaling show that important socioeconomic city characteristics such as wealth and innovation capacity exhibit a nonlinear, particularly a power law scaling with population size. These nonlinear effects are common to all cities, with similar power law exponents. These findings mean that the larger the city, the more dispropor...

Some scholarly publications or patent publications may signal breakthroughs in basic scientific research or radical new technological developments. Are there bibliographical indicators that enable an analysis of R&D dynamics to help identify these `local revolutions' in science and technology? In this case study we focus on developments that occurr...

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 glob...

We investigated the interdisciplinary ‘pillars’ of scientific knowledge on which the emerging field of sustainability science is founded, using a bibliometric approach and data from the Web of Science database. To find this scientific basis, we first located publications that represent a relevant part of sustainability science and then extracted th...

In this paper we present a compilation of journal impact properties in relation to other bibliometric indicators as found in our earlier studies together with new results. We argue that journal impact, even calculated in a sufficiently advanced way, becomes important in evaluation practices based on bibliometric analysis only at an aggregate level....

Radicchi, Fortunato, and Castellano [arXiv:0806.0974, PNAS 105(45), 17268] claim that, apart from a scaling factor, all fields of science are characterized by the same citation distribution. We present a large-scale validation study of this universality-of-citation-distributions claim. Our analysis shows that claiming citation distributions to be u...

We investigated the occurrence of non-alphanumeric characters in a randomized subset of over almost 650,000 titles of scientific publications from the Web of Science database. Additionally, for almost 500,000 of these publications we correlated occurrence with impact, using the field-normalised citation metric CPP/FCSm. We compared occurrence and c...

The obsolescence and "durability" of scientific literature have been important elements of debate during many years, especially regarding the proper calculation of bibliometric indicators. The effects of "delayed recognition" on impact indicators have importance and are of interest not only to bibliometricians but also among research managers and s...

Opthof and Leydesdorff (Scientometrics, 2011) reanalyze data reported by Van Raan (Scientometrics 67(3):491-502, 2006) and conclude that there is no significant correlation between on the one hand average citation scores measured using the CPP/FCSm indicator and on the other hand the quality judgment of peers. We point out that Opthof and Leydesdor...

We applied a set of standard bibliometric indicators to monitor the scientific state-of-arte of 500 universities worldwide and constructed a ranking on the basis of these indicators (Leiden Ranking 2010). We find a dramatic and hitherto largely underestimated language effect in the bibliometric, citation-based measurements of research performance w...

We present an empirical comparison between two normalization mechanisms for citation-based indicators of research performance. These mechanisms aim to normalize citation counts for the field and the year in which a publication was published. One mechanism is applied in the current so-called crown indicator of our institute. The other mechanism is a...

We define converging research as the emergence of an interdisciplinary research area from fields that did not show interdisciplinary connections before. This paper presents a process to search for converging research using journal subject categories as a proxy for fields and citations to measure interdisciplinary connections, as well as an applicat...

A useful guide to citation analysis shows that counting publications is harder than it looks, finds Ton van Raan.

In this study we show that it is possible to identify top-cited publications other than Web of Science (WoS) publications, particularly non-journal publications, within fields in the social and behavioral sciences. We analyzed references in publications that were themselves highly cited, with at least one European address. Books represent between 6...

We reply to the criticism of Opthof and Leydesdorff on the way in which our institute applies journal and field normalizations to citation counts. We point out why we believe most of the criticism is unjustified, but we also indicate where we think Opthof and Leydesdorff raise a valid point.

The crown indicator is a well-known bibliometric indicator of research performance developed by our institute. The indicator aims to normalize citation counts for differences among fields. We critically examine the theoretical basis of the normalization mechanism applied in the crown indicator. We also make a comparison with an alternative normaliz...

Converging research is the emergence of new interdisciplinary research from fields which showed limited mutual interdisciplinary connections before. We describe three search strategies to identify converging research using data extracted from the WoS, including the social sciences and humanities. The field-to-field references (FFR) strategy uses ci...

The study of the citation histories and ageing of documents are topics that have been addressed from several perspectives, especially in the analysis of documents with “delayed recognition” or “sleeping beauties.” However, there is no general methodology that can be extensively applied for different time periods or research fields. In this article,...

Research performance, research networks and research profiles of EU countries

The representation of science as a citation density landscape and the study of scaling rules with the field-specific citation density as a main topological property was previously analyzed at the level of research groups. Here, the focus is on the individual researcher. In this new analysis, the size dependence of several main bibliometric indicato...

Previous research has demonstrated that lower performance groups have a larger size-dependent cumulative advantage for receiving citations than do top-performance groups. Furthermore, regardless of performance, larger groups have less not-cited publications. Particularly for the lower performance groups, the fraction of not-cited publications decre...

A representation of science as a citation density landscape is proposed and scaling rules with the field-specific citation density as a main topological property are investigated. The focus is on the size-dependence of several main bibliometric indicators for a large set of research groups while distinguishing between top-performance and lower-perf...

The statistical properties of bibliometric indicators related to research performance, field citation density, and journal impact were studied for the 100 largest European research universities. A size-dependent cumulative advantage was found for the impact of universities in terms of total number of citations. In the author's previous work, a simi...

The statistical properties of bibliometric indicators related to research performance, field citation density, and journal impact were studied for the 100 largest European research universities. A size-dependent cumulative advantage was found for the impact of universities in terms of total number of citations. In the author's previous work, a simi...

For the 100 largest European universities we studied the statistical properties of bibliometric indicators related to research performance, field citation density and journal impact. We find a size-dependent cumulative advantage for the impact of universities in terms of total number of citations. In previous work a similar scaling rule was found a...

In this paper we distinguish between top-performance and lower performance groups in the analysis of statistical properties of bibliometric characteristics of two large sets of research groups. We find intriguing differences between top-performance and lower performance groups, but also between the two sets of research groups. Particularly these la...

In this article we present an empirical approach to the study of the statistical properties of bibliometric indicators on a very relevant but not simply “available” aggregation level: the research group. We focus on the distribution functions of a coherent set of indicators that are used frequently in the analysis of research performance. In this s...

In this paper we present characteristics of the statistical correlation between the Hirsch (h-) index and several standard bibliometric indicators, as well as with the results of peer review judgment. We use the results of a large evaluation study of 147 university chemistry research groups in the Netherlands covering the work of about 700 senior r...

Mapping of science is studied in this project along several different lines. First, a critical elaboration of the classical method of co-citation duster analysis, developed by the Institute for Scientific Information (ISI), is carried out. Secondly, a multi-database approach, focused on improvement of the interpretability of co-citation cluster str...

This paper describes an approach t o monitoring scientific progress in chemical engineering in order t o operationalize concepts such a s 'research performance' which can be used in the retrospective evaluation and the future anticipation of scientific research activities. We focus on various quantitative methods. Bibliometric methods form an impor...

By analyzing the distribution of publications as a function of received citations, a relation was found between the deciles of this distribution and the number of citations. This relation suggests a model analogous to Beer's Law in physics on the absorption of Light in a homogenous layer of absorbing material. The results show a remarkable constanc...

We introduce quasi-correspondence analysis, a new method for mapping interrelations between publishing scientific entities, e.g. journals. It is based on the spatial configurations resulting from the analysis of the following bibliometric data: the relations in the citation-structure, which are examined for both the cited and citing-mode of scienti...

Summary A system of input, output, and efficiency indicators is sketched out, with each indicator related to basic research, applied research, and experimental development. Mainly, this scheme is inspired by empirical innovation economics (represented in Germany, e.g., by H. Grupp) and by “advanced bibliometrics' and scientometrics (profiled by van...

After a review of developments in the quantitative study of science, particularly since the early 1970s, I focus on two current main lines of ‘measuring science’ based on bibliometric analysis. With the developments in the Leiden group as an example of daily practice, the measurement of research performance and, particularly, the importance of indi...

In this rejoinder, I structure my comments around a number of main topics dis-cussed by the authors of the commentaries. ASSESSMENT OF THE BIBLIOMETRIC INSTRUMENT This is an important point (Veugelers, this issue): As in all empirical research, one has to know not only "what" is measured, but also "with what" one is mea-suring. In other words, one...

In this paper we discuss recent developments in rankings of universities and the impact of these rankings on academia in the context of international benchmarking and evaluation. We focus on technical and methodological problems behind these rankings, particularly those based on bibliometric methods, with special attention to the social sciences an...

This article presents an overview of measuring science based on a bibliometric meth- odology. The 2 main lines of this methodology are discussed. First, the measurement of research performance is addressed, including aspects such as interdisciplinarity, collaboration, and knowledge users. It is demonstrated that advanced bibliometric methods are an...

Maps of science provide visualizations of scientific knowledge domains by quantitatively grouping elements from scientific papers. In evaluative bibliometric studies these quantitative maps have proven a useful tool Representation schemes such as mental maps or cognitive maps provide a tool to structure qualitative reasoning about, for instance, st...

A ‘Sleeping Beauty in Science’ is a publication that goes unnoticed (‘sleeps’) for a long time and then, almost suddenly, attracts a lot of attention (‘is awakened by a prince’). We here report the -to our knowledge- first extensive measurement of the occurrence of Sleeping Beauties in the science literature. We derived from the measurements an ‘aw...

After a review of developments in the quantitative study of science, particularly since the early 1970s, I focus on two current main lines of ‘measuring science’ based on bibliometric analysis. With the developments in the Leiden group as an example of daily practice, the measurement of research performance and, particularly, the importance of indi...

In this paper we report first results of our study on network characteristics of a reference-based, bibliographically coupled (BC) publication network structure. We find that this network of clustered publications shows different topologies depending on the age of the references used for building the network. A remarkable finding is that only the n...

The authors provide an overview of advanced bibliometric methods for (a) an objective and transparent assessment of journal performance and (b) positioning of a journal in relation to other journals. These methods are applied to Psychotherapy Research, an international journal within the field of clinical psychology. In the first analysis, the auth...

Evaluation studies of scientific performance conducted during the past years more and more focus on the identification of research of the 'highest quality', 'top' research, or 'scientific excellence'. This shift in focus has lead to the development of new bibliometric methodologies and indicators. Technically, it meant a shift from bibliometric imp...