Teams in R&D: Evidence from Inventor Data

The size of research teams in universities and in industrial R&D has steadily increased over the last several decades. What explains the rising importance of teamwork in science and in industrial R&D? Teamwork is growing even in fields with little growth in research employment, suggesting that greater returns to specialization explain only part of the story. This paper exploits a panel dataset of researchers that includes all inventors listed on U.S. patents since 1975 to investigate the increasing importance of teamwork in industrial R&D. Beyond simply characterizing team size, we develop new and useful stylized facts about inventor teams from a static as well as a dynamic perspective. We develop a model of dynamic team formation, where a firm risks appropriation of its intellectual property by leaving scientists.  We then evaluate its implications for team size, team persistence and team composition.