The acquisition of external R&D positively affects the creation of innovative products; however, as external R&D intensity and complexity increase, firms may face higher costs of coordination and control. Recent literature has found evidence of the R&D over-outsourcing problem analyzing single-country small samples of firms. Moreover, most research has overlooked the endogeneity problems that can arise with firms' decisions on R&D. We investigate the external R&D–product innovation association, controlling for different types of research sources in a large collection of firms in five European countries. We find that external R&D enhances innovation outcomes until a certain threshold; beyond this threshold, firms face over-outsourcing. Furthermore, R&D acquired from universities shows to be most effective in promoting product innovations, whereas R&D acquired from firms within the same group has a larger effect on the intensity of innovative product sales.

外部研发的收购对创新产品的创造产生积极影响；然而，随着外部研发强度和复杂性的增加，企业可能面临更高的协调和控制成本。最近的文献在分析单一国家的小样本公司时发现了研发过度外包问题的证据。此外，大多数研究都忽略了企业在研发决策中可能出现的内生性问题。我们调查了外部研发 - 产品创新协会，控制了五个欧洲国家的大量公司中不同类型的研究来源。我们发现外部研发在达到一定阈值之前会增强创新成果；超过这个门槛，公司就会面临过度外包。此外，R&