1. Tito Boeri is Professor of Economics, Bocconi University, Milan, Italy.
2. Giulia Giupponi is Postdoctoral Fellow, Institute for Fiscal Studies, London, United Kingdom. In September 2020, she will be Assistant Professor of Economics, Bocconi University, Milan, Italy.
3. Alan B. Krueger was the James Madison Professor of Political Economy, Princeton University, Princeton, New Jersey, before his death on March 16, 2019.
4. Stephen Machin is Professor of Economics and Director of the Centre for Economic Performance, London School of Economics, London, United Kingdom.