To prepare for the 2008 Olympic Games, China adopted a number of radical measures to improve air quality. Using officially reported air pollution index (API) from 2000 to 2009, we show that these measures improved the API of Beijing during and after the Games, but 60% of the effect faded away by...

We aim to quantify the role of social networks in job-related migration. With over 130 million rural labors migrating to the city each year, China is experiencing the largest internal migration in the human history. Using instrumental variables in the 2006 China Agricultural Census, we find that...

This essay reviews the theoretical and empirical literature on quality disclosure and certification. After comparing quality disclosure with other quality assurance mechanisms and describing a brief history of quality disclosure, we address three key theoretical issues: (i) Why don't sellers...

Focusing on 8 drug types on the WHO-approved medicine list, we constructed an original dataset of 899 drug samples from 17 low- and median-income countries and tested them for visual appearance, disintegration, and analyzed their ingredients by chromatography and spectrometry. Fifteen percent of...

Using peer-to-peer (P2P) lending as an example, we show that learning by doing plays an important role in alleviating the information asymmetry between market players. Although the P2P platform (Prosper.com) discloses part of borrowers' credit histories, lenders face serious information problems...

"Using sportscard grading as an example, we employ field experiments to investigate the informational role of professional certifiers. Empirical results suggest three patterns: first, the grading certification provided by the first professional certifier offers new information to inexperienced...

This essay reviews the theoretical and empirical literature on quality disclosure and certification. After comparing quality disclosure with other quality assurance mechanisms and describing a brief history of quality disclosure, we address two sets of theoretical issues. First, why don't...

Using 2006 China Agricultural Census (CAC), we examine whether the introduction of the New Cooperative Medical System (NCMS) has affected child mortality, maternal mortality, and school enrollment of the 6-16 years olds. Our data cover 5.9 million people living in eight low-income rural...

Every new method of trade offers an opportunity for economic agents to compare its costs and benefits relative to the status quo. Such comparison motivates sorting across market segments and reshapes the whole marketplace. The Internet provides an excellent example: it introduces substantial...