France has experienced massive changes in its regulation of working time during the last decade. These changes generate natural experiments that may help to study a variety of issues in labor economics, including work sharing effect on job creation or productivity, labor relations or adaptation...

The randomized trial literature has helped to renew the fields of microeconometric policy evaluation by emphasizing identification issues raised by endogenous program participation. Measurement and attrition issues have perhaps received less attention. This paper analyzes the dramatic impact of...