Four recently published RCTs of US Mayors' programs providing unconditional cash to low-income people - in Los Angeles, Cambridge MA, Stockton CA, and Baltimore - claimed positive results (and got strong press coverage). Quick take: Unfortunately, the results are unreliable due to high sample loss.
Programs and Study Designs:
Each program gave low-income individuals a guaranteed income of $500-1000 per month for 1-2 years. The RCT samples ranged from 286 individuals (Cambridge) to 8,194 (Los Angeles).
The studies claimed positive effects on economic, health and other outcomes, based on surveys of sample members.
Study Quality:
Unfortunately, the studies all suffered from high sample loss ("attrition") that differed between treatment (T) and control (C) groups. Attrition rates were: 27% T vs 65% C in Los Angeles; 22% T vs 37% C in Cambridge; 51% T vs 60% C in Stockton; and 27% T vs 45% C in Baltimore.
These attrition rates create "unacceptable levels of potential bias" under What Works Clearinghouse standards. Treatment and Control group members essentially self-selected themselves out of the sample, and did so at different rates and for different reasons, undermining equivalence between the two groups.
Comments:
The studies' claims of positive effects nevertheless received uncritical press coverage, including in The Washington Post, The Economist, The Baltimore Sun, and Los Angeles Times.
Unconditional cash programs are a hot policy topic in the US. Fortunately, there are other ongoing or completed RCTs of such programs without serious attrition or other problems. We hope that policymakers and journalists will rely on the results of these valid studies, whose results to date we've previously summarized: Texas and Illinois Unconditional Cash Transfers, Chelsea Eats, and Baby's First Years.