Agricultural Economics Department



Lilyan Fulginiti

Date of this Version

Fall 2017


Wang, S.L., Plastina, A., Fulginiti, L.E. and Ball, E. (2017) Benefits of Public R & D in US Agriculture:Spill-Ins, Extension, and Roads. Theoretical Economics Letters , 7, 1873-1898.


This paper uses panel data for the 1980-2004 period to estimate the contributions

of public research to US agricultural productivity growth. Local and social

internal rates of return are estimated accounting for the effects of R & D

spill-in, extension activities and road density. R & D spill-in proxies were constructed

based on both geographic proximity and production profile to examine

the sensitivity of the rates of return to these alternatives. We find that

extension activities, road density, and R & D spill-ins, play an important role

in enhancing the benefit of public R & D investments. We also find that the

local internal rates of return, although high, have declined through time along

with investments in extension, while the social rates have not. Yet, the social

rates of return are not robust to the choice of spill-in proxy.