The rise and fall of RD networks

Drawing on a large database of publicly announced RD alliances.we track the evolution of RD networks in a large number of economic sectors over a long time period 1986 2009.Our main goal is to evaluate temporal and sectoral robustness of the main statistical properties of empirical RD networks. By studying a large set of indicators, we provide a more complete description of these networks with respect to the existing literature. We find that most network properties are invariant across sectors. In addition, they do not change when alliances are considered independently of the sectors to which partners belong. Moreover, we find that many properties of RD networks are characterized by a rise-andfall dynamics with a peak in the mid-nineties. Finally, we show that such properties of empirical RD networks support predictions of the recent theoretical literature on RD network formation.