Rafael La Porta mailed letters to nonexistent businesses in 159 countries and waited to see which were sent back to the campus in Hanover, N.H.
After a year, 59 percent had returned. Only four countries sent the letters back within 90 days _ the United States, El Salvador, the Czech Republic and Luxembourg.
The goal was to use a simple and universal service to explore why, other than corruption, most developing countries have poorly performing governments. The economists say the results suggest that governments in developing countries are plagued by the same inefficiencies as the private sector.