I have written a few times about the frustration when policy makers ignore the advice of economists. Yet, there are a few cases where economists were given free reign over the design of policy interventions, which not only allowed to obtain positive outcomes but also useful information for further study.
Nora Lustig reports about Progresa, the Mexican cash transfers program designed to elicit parents to send their kids to school and make sure necessary health check-ups were attended. From the start, the program was designed and administrated by people with an academic background. Progresa has worked remarkably well, to the point that it was not only not scrapped, as is usual, with presidential changes, its coverage also kept increasing. The only setback was a name change to Oportunidades. The critical ingredient to this success was the scholarly involvement, that not only designed it for success, but also provided the tools to measure this. And along with that a wealth of data that has allowed to understand even better what makes good intervention in practice.