“…Due to confidentiality rules, we could not retrieve information about individual scientific productivity; the "Robustness tests" section explored the possibility of a systematic productivity gap between mobile and non-mobile, foreign and national researchers, and found little support in this respect. Other relevant factors, such as personal ties (e.g., Fisman et al, 2018;Hadlock & Pierce, 2021) or institutional prestige and ties (Burris, 2004), were not explored. Moreover, future research needs to shed more light on differences within the group of mobile and foreign scientists, based, for instance, on the prestige of institution of origin and the strength of scientific relationships between two countries, as well as explore more in depth the reasons underpinning the effect of important variables such as gender, and type of funding support, which are beyond the scope of this study.…”