The critical element that distinguishes classical experiments from all other modes of analysis is the random assignment of treatment to enrollees in a study. This paper examines the major methodological advantages of random assignment for the purpose of estimating the effectiveness of current...

A popular proposal for reforming social security is to supplement or replace traditional publicly financed benefits with a new system of mandatory defined-contribution private pensions. Proponents claim that private plans offer better returns than traditional social security. To achieve higher...