Abstract
As an essential part of the academic environment, international scientific mobility draws considerable attention from researchers. Previous studies have indicated a strong relationship between scientific mobility and scientific output. However, few researchers have addressed the causality between them. The research questions in this study focused on how the international scientific mobilization of the researchers affects their number of international collaborations, their ability to get published at higher impact factor journals, the number of citations that they get. Based on the SCOPUS database of English language scientific journal articles, this paper revealed the causal effects of international scientific mobility of the researchers on their scientific productivity, collaborations, and impact on science using the synthetic control method. The author’s affiliation on their articles provided the geographical location that can be tracked in time to infer the international scientific mobility of each author. A sample of more than 79,000 immobile scientists was used to create the synthetic versions of over 1500 internationally mobile scientists, so that, the synthetic version of each mobile author best resembled the academic ability of her/his counterpart mobile author in the pre-mobilization period. This allowed investigating the effects of the international mobilization on their publications by comparing the post-mobilization publication characteristics of the mobile authors and their immobile synthetic controls.The findings show strong evidence of a substantial positive effect of scientific mobility on the ability to get published in more prestigious journals, the number of citations received in total and from overseas, and international collaborations. The magnitude of the effect is conditional on the duration of scientific mobility.
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STATA is used for statistical procedures. GIMP is used for the Figures.
Notes
Short-term migration of highly skilled labor for employment, visiting, and training purposes.
The number of observed mobility is 7615 between Turkey and the USA for the years 2006–2016. The number of total mobility between the USA and the developing World is 201,067 for the same period. Turkey ranks the 2nd after Iran when countries are weighted by their population and 7th on level (OECD, 2017).
More information and their practical contributions to the methodology are discussed in the Methodology part of the paper. Shortly, one of these regulations led back to 1935 and requires all the citizens to have “pure” Turkish family names which make it possible to identify Turkish scientists. The other regulation limits the number of foreign citizens to 2% in Turkish Universities—delegated legislation no:75 dated 09.02.1983—which enables us to construct a more identified data set.
There are several programs of The Scientific and Technological Research Council of Turkey (TUBITAK) which makes significant amounts of resources available for research purposes, compensations, grants, various kinds of allowances for the family of the returner researchers and the returner researchers themselves (http://www.tubitak.gov.tr/en). The period of the grants vary between 1 and 36 month, and the total funding available for each return project is nearly up to 500.000 $ depending on the length and content of the project. Some other countries such as Germany, Australia, and China have carried out similar brain gain oriented programs for their elite scientists abroad. See Wang et al. (2019), Laudel (2003), and Jonkers (2008) for a more detailed discussion about these kinds of programs.
OECD calculations based on the affiliation information of the authors who have published scientific articles on Scopus between 2006 and 2016. See the Methodology section for more information.
As the number of non-self-citations.
The institutional affiliations in the bibliometric data may not necessarily screen the location that the research has been made but according to Appelt et al. (2015: 9) it can be assumed that the affiliation shows some form of "intellectual presence".
There are also different measurement ways of scientific mobility in the literature. Laudel (2003) and Appelt et al. (2015) have compiled different techniques that has been used in the literature such as encyclopedias of scientists (Allison & Long, 1987), information gathered from scientific associations (Stephan & Levin, 2001), census data and surveys (Shauman & Xie, 1996), curriculum vitaes (Canibano et al., 2011; Dietz et al., 2000), specific survey designs (Auriol, 2010; Auriol et al., 2013; Franzoni et al., 2012; Stephan & Levin, 2001) and bibliometric methods (Pierson & Cotgreave, 2000).
Laudel assumes that researchers' first publications are derived from their PhD dissertations. Thus, their affiliation on their first publication is assumed to be the starting of their academic career and mobility history.
The SCOPUS data that is used in this study does not cover all publications in 2014. Thus, excluding this year would result more robust coverage evaluation.
This assumption seems to be reasonable since the number of non-Turkish named authors with a Turkish affiliation who were in the sample because of the fact that they were a co-author in an article written by a Turkish-named author is miniscule. Under any circumstances, this assumption may yield a small underestimation of the coverage rate in the worst case.
Because of the limitations on the Turkish names and surnames list that were used for the matching process.
All Science Journal Classification (ASJC) scheme is used to classify the journals and the articles. For a detailed information on ASJC, see https://service.elsevier.com/app/answers/detail/a_id/14882/supporthub/scopus/~/what-are-the-most-frequent-subject-area-categories-and-classifications-used-in/.
The limitations on “very unique” scientists can be gradually relaxed. As a robustness check, these “very unique” scientists are included in the analyisis by relaxing the criteria for being in the donor group to construct the synthetics of them. The results are robust.
Parallel trend is the assumption that the treatment is the only shock the system of treated cases within the observed time frame (Robbins et al., 2017).
Either of physical, health or life sciences. Social sciences are excluded due to the insufficient number of observations on English language social science articles published by Turkish authors in SCOPUS. Turkish social scientists mostly tend to publish on Turkish social science journals and there are very few Turkey based social science journals indexed in SCOPUS compared to the number of journals of other disciplines. This phenomenon also showed at the SCOPUS data that, the number of Turkish social scientists in SCOPUS database is not enough to carry out a reasonable research on them.
The calendar year of the first English language article in SCOPUS is let to vary 5 years to control the age and the scientific environment changes by time as well as the stages of the academic progress of the authors.
SHC is the researcher's level of knowledge and scientific expertise, the stock of a researcher’s scientific and technological knowledge and skills (Jonkers & Tijssen, 2008: 313).
Scientific social capital is researcher's stock of relevant professional ties, researcher's relations's quantity, quality or intensity with the other writers (Jonkers & Tijssen, 2008: 313).
As mentioned in the the Data section, the final data used in the SCM contains 1601 mobile scientists after excluding 146 authors who published in a different discipline in the USA and 174 authors who have a very unique publication pattern such as first publication date, very low number of publications and publishing frequency so that their donor group couldn’t be constructed.
As a robustness check, the authors who published only two articles –one at the USA and one at Turkey- are exluded to control the possibility that these scientists cause the sharp peaks at the graphs. The results are almost identical.
Moed et al. (2013) categorizes the stays at the host country in three types, short stays (scholarships, visiting and post-doc positions that are less than 2 years), longer stays (double post-doc periods and temporary stuff members that are more than 2 years) and permanent stays. In this study, the stays are cetegorized in two types, shorters stays (1 year or less) and longer stays (more than 1 year) because the vast majority of the locally available scholarhips for international academic mobility is less than 1 year in Turkey. Visits more than 1 year strongly imply an additional financial allowance in the USA (usually secured by double post-doc activity and being temporary stuff members). Permanenet stays are not included in the categorization due to the likely potential of a complication arising from the nature of the bibliometric data that the affiliation on the last published paper can hardly imply a permanent stay in that country.
The data doesn’t allow to track the authors in monthly basis. Thus, the authors are classified by their duration in the USA annually, ignoring that the duration may even be shorter than a month between two articles published in succesive years. At this point, it is assumed that this doesn’t change the nature of the findings.
The returnees who stayed for one year or less and the returnees who stayed for more than one year at the USA are not statistically different in terms of their ability to publish at a high IF journal, the number of citations they receive and their international collaborations before their mobilization to the USA.
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Acknowledgements
First and foremost, I would like to express my gratitude to Richard B. Freeman of Harvard and NBER for his continuous guidance and support. I gratefully thank Dr. Xi Hu from the University of Oxford for her support in collecting data from Scopus. I am also grateful to Jennifer Amadeo-Holl, Yasin Ozcan, Sifan Zhou, Lisa Ursino, Mohan Ramanujan, Dan Feenberg for their kind help at the NBER. Finally, I would like to extend my thanks to Ali Firat Atabas “Afa”, Elaine Bernard, Sharon Block, John “Jack” Trumpour, and David Kunst for their valuable help and support.
Funding
The research leading to these results received funding from Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) under Grant Agreement No: 2219 for the first year and financial research support (Wertheim Fellowship) from the Labour and Worklife Program of Harvard University for the second year.
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Findings of this research was presented in EC 2888e Economics of Science and Engineering Workshop of Harvard Business School and Harvard Department of Economics on 13 April 2018, at Bloomberg Center, HBS, Cambridge, MA.
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Aykac, G. The value of an overseas research trip. Scientometrics 126, 7097–7122 (2021). https://doi.org/10.1007/s11192-021-04052-4
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DOI: https://doi.org/10.1007/s11192-021-04052-4
Keywords
- Scientist mobility
- High-skilled labor
- High-skilled labor migration
- Brain drain
- Bibliometrics
- Scientific productivity