As someone else said, use multiple KPIs that describe an ideal individual who is reformed. Recidivism rate, average annual income over the next 10 years, healt

As someone else said, use multiple KPIs that describe an ideal individual who is reformed. Recidivism rate, average annual income over the next 10 years, health/estimated life-span of the reformed individual. Will prisons try to find ways to cheat? That's fine, we'll just reserve the right to redefine the KPIs every year for all new prisoners. But making such a change is difficult, because of "tough on crime" politicians who believe the only way to reduce crime is harsh justice- when in modern times that simply isn't true any more.