Quality certification is a common tool to reduce asymmetric information and enhance trust in marketplaces. Should the certificate focus on seller inputs such as fast shipping, or include output measures such as consumer ratings? In theory, incorporating output measures makes the certificate more...

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...