This paper considers the evidence on the effectiveness and limitations of randomized controlled trials in economics. I revisit my previous paper quot;Randomization and Social Policy Evaluationquot; and update its message. I present a brief history of randomization in economics and identify two...

This paper considers the problem of policy evaluation in a modern society with heterogeneous agents and diverse groups with conflicting interests. Several different approaches to the policy evaluation problem are compared including the approach adopted in modern welfare economics, the classical...

This paper estimates the long-term benefits from an influential early childhood program targeting disadvantaged families. The program was evaluated by random assignment and followed participants through their mid-30s. It has substantial beneficial impacts on health, children's future labor...