Mechanism Reform: An Application to Child Welfare

In many market-design applications, a new mechanism is introduced to reform an existing institution. Compared to the design of a mechanism in isolation, the presence of a status-quo system introduces both challenges and opportunities for the designer. We study this problem in the context of reforming the mechanism used to assign Child Protective Services (CPS) investigators to reported cases of child maltreatment in the U.S. CPS investigators make the consequential decision of whether to place a child in foster care when their safety at home is in question. We develop a design framework built on two sets of results: (i) an identification strategy that leverages the status-quo random assignment of investigators—along with administrative data on previous assignments and outcomes—to estimate investigator performance; and (ii) mechanism-design results allowing us to elicit investigators’ preferences and efficiently allocate cases. This alternative mechanism can be implemented by setting personalized non-linear rates at which each investigator can exchange various types of cases. In a policy simulation, we show that this mechanism reduces the number of investigators’ false positives (children placed in foster care who would have been safe in their homes) by 10% while also decreasing false negatives (children left at home who are subsequently maltreated) and overall foster care placements. Importantly, the mechanism is designed so that no investigator is made worse-off relative to the status quo. We show that a naive approach which ignores investigator preference heterogeneity would generate substantial welfare losses for investigators, with potential adverse effects on investigator recruitment and turnover.