The trade and welfare impacts of multilateral liberalization on individual countries and groups within countries depend on many factors-including the depth of liberalization by trading partners, the extent of countries' own reforms, the responsiveness of investors to changes in relative prices and market opportunities, and actions by governments to reduce real trade costs. The magnitude of erosion will depend on a variety of factors, including the product and country coverage of preferential schemes, the level of most favored nation restrictions in the markets granting preferential access, the administrative costs associated with using preference programs, the incidence of any preference rents, the depth of liberalization realized in Doha, and the existence of and changes in reciprocal trade agreements. Moreover, the value of preferences is better measured by income earned-what matters is the impact on the price actually received by the exporters because the pass-through of preferential access is likely to be incomplete.