This series is produced by the Health, Nutrition, and Population Global Practice of theWorld Bank. The papers in this series aim to provide a vehicle for publishing preliminaryresults on HNP topics to encourage discussion and debate. The findings, interpretations,and conclusions expressed in this paper are entirely those of the author(s) and should notbe attributed in any manner to the World Bank, to its affiliated organizations, or to membersof its Board of Executive Directors or to the