Causal estimates of the benefits of increased schooling using US state schooling laws as instruments typically rely on specifications which assume common trends across states in the factors affecting different birth cohorts. Differential changes across states during this period, such as relative school quality improvements, suggest that this assumption may fail to hold. Across a number of outcomes including wages, unemployment, and divorce, we find that statistically significant causal estimates become insignificant and, in many instances, wrong-signed when allowing year of birth effects to vary across regions.

This paper studies an optimal renegotiation protocol designed by a benevolent planner when two countries renegotiate with the same lender. The solution calls for recoveries that induce each country to default or repay, trading off the deadweight costs and the redistribution benefits of default independently of the other country. This outcome contrasts with a decentralized bargaining solution where default in one country increases the likelihood of default in the second country because recoveries are lower when both countries renegotiate. The paper suggests that policies geared at designing renegotiation processes that treat countries in isolation can prevent contagion of debt crises.