This article analyses the effect of degree of interdisciplinarity on the citation impact of individual publications for four different scientific fields. We operationalise interdisciplinarity as disciplinary diversity in the references of a publication, and rather than treating interdisciplinarity as a monodimensional property, we investigate the separate effect of different aspects of diversity on citation impact: i.e. variety, balance and disparity. We use a Tobit regression model to examine the effect of these properties of interdisciplinarity on citation impact, controlling for a range of variables associated with the characteristics of publications. We find that variety has a positive effect on impact, whereas balance and disparity have a negative effect. Our results further qualify the separate effect of these three aspects of diversity by pointing out that all three dimensions of interdisciplinarity display a curvilinear (inverted U-shape) relationship with citation impact. These findings can be interpreted in two different ways. On the one hand, they are consistent with the view that, while combining multiple fields has a positive effect in knowledge creation, successful research is better achieved through research efforts that draw on a relatively proximal range of fields, as distal interdisciplinary research might be too risky and more likely to fail. On the other hand, these results may be interpreted as suggesting that scientific audiences are reluctant to cite heterodox papers that mix highly disparate bodies of knowledge—thus giving less credit to publications that are too groundbreaking or challenging.

COMMENTMeasuring the global movements of researchers will help to assess the effects of political actions on science.© 2 0 1 7 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e . A l l r i g h t s r e s e r v e d .

One of a number of new research fields to emerge over the last four or five decades is Science and Technology Studies (STS). This paper attempts to identify the core contributions to this emerging field. Following the methodology developed by Fagerberg and Sapprasert (2010) in their parallel study of Innovation Studies, it adopts the perspective of the authors of individual chapters in a number of authoritative 'handbooks', analysing the references cited by these authors. The assumption is that these authors will collectively have been reasonably systematic and comprehensive in their efforts to identify the core contributions to the field of STS. The study analyses those publications that have been most highly cited by the handbook authors, examining the content of those core publications and what they reveal about the various phases in the development of STS, as well as identifying the most prominent authors and the institutions in which they are based. In the second part of the empirical study, we analyse the 'users' of the STS core contributions -in other words, the authors that have cited these contributions in their own work. This includes looking at the research fields of the users, the journals in which they publish, and their geographical location. The paper concludes with some comparisons between STS and the fields of Innovation Studies and Entrepreneurship, in particular with regard to the role of 'institution builders' in helping to develop a new research field.

This paper presents a methodological framework for developing scientific mobility indicators based on bibliometric data. We identify nearly 16 million individual authors from publications covered in the Web of Science for the 2008-2015 period. Based on the information provided across individuals' publication records, we propose a general classification for analyzing scientific mobility using institutional affiliation changes. We distinguish between migrants--authors who have ruptures with their country of origin--and travelers--authors who gain additional affiliations while maintaining affiliation with their country of origin. We find that 3.7% of researchers who have published at least one paper over the period are mobile.Paper accepted for publication in Journal of Informetrics 2 Travelers represent 72.7% of all mobile scholars, but migrants have higher scientific impact. We apply this classification at the country level, expanding the classification to incorporate the directionality of scientists' mobility (i.e., incoming and outgoing). We provide a brief analysis to highlight the utility of the proposed taxonomy to study scholarly mobility and discuss the implications for science policy.