Information Economics: Adverse Selection, Moral Hazard, and Signaling

Overview

Information economics studies how asymmetric information between parties causes market failures and shapes institutional responses. Akerlof's "market for lemons" shows adverse selection can collapse entire markets; Spence's signaling model shows informed parties can credibly convey quality through costly actions; Rothschild-Stiglitz screening shows uninformed parties can design menus that induce self-selection. Together, these frameworks explain why markets for insurance, credit, labor, and used goods systematically deviate from the competitive ideal and why institutions like warranties, credentials, and regulation exist.

When to Use

• Diagnosing why a market is failing or shrinking (quality collapse, credit rationing, insurance death spirals)
• Evaluating whether a signal (degree, certification, warranty) is credible and efficient
• Designing screening mechanisms (menus, deductibles, trial periods) to sort heterogeneous agents
• Assessing policy interventions (mandatory disclosure, minimum standards, subsidized insurance)

When NOT to Use

• Information is symmetric or costlessly verifiable (no asymmetry problem)
• The product is a pure experience good where reputation and repeat purchase fully resolve quality uncertainty
• The analysis requires modeling strategic interaction beyond bilateral (use full game-theoretic models)