Should Workplace Programs Be Voluntary or Mandatory? Evidence from a Field Experiment on Mentorship

Abstract

In a field experiment, we find large differences in productivity treatment effects between voluntary and mandatory workplace mentorship programs. A significant portion of this difference is due to the best employees opting into the program when it is voluntary and these employees having the smallest treatment effects. Our findings suggest that pilot programs run on a voluntary group may obfuscate large potential gains. In our setting, the firm cannot rely on self-selection to help with program allocation because employees that benefit the most from the program are the least likely to participate. Our findings have implications for program evaluation, experimental design, productivity dispersion, and inequality.