According to economists Michael Clemens and Lant Pritchett, "permitting people to move from low-productivity places to high-productivity places appears to be by far the most efficient generalized policy tool, at the margin, for poverty reduction". A successful two-year in situ anti-poverty program, for instance, helps poor people make in a year what is the equivalent of working one day in the developed world. A slight reduction in the barriers to labor mobility between the developing and developed world would do more to reduce poverty in the developing world than any remaining trade liberalization.