Agricultural research has transformed agriculture and in doing so contributed to the transformation of economies. Economic issues arise because agricultural research is subject to various market failures, because the resulting innovations and technological changes have important economic...

Commissioned by the CGIAR Science Council and prepared as a Background Paper for the 2008 World Development Report of the World Bank.

Replaced with revised version of paper 07/10/09.

We use newly constructed state-specific data to explore the implications of common modeling choices for measures of research returns. Our results indicate that state-to-state spillover effects are important, that the research and development lag is longer than many studies have allowed, and that...