The "common effect" model in program evaluation assumes that all treated individuals have the same impact from a program. Our paper contributes to the recent literature that tests and goes beyond the common effect model by investigating impact heterogeneity using data from the experimental...

We analyse how physicians respond to contractual changes and incentives within amultitasking environment. In 1999 the Quebec government (Canada) introduced an optionalmixed compensation system, combining a fixed per diem with a discounted (relative to thetraditional fee-for-service system) fee...