This article was originally published with an error in the affiliation of one of the authors.
The affiliation of Leah R. Rosenzweig was given as Center for Global Development, University of Chicago, Washington, DC, USA. The correct affiliation is Center for Global Development, Washington DC, USA and Development Innovation Lab, University of Chicago, Chicago, IL, USA.
This has now been corrected and the original PDF and HTML updated.
The authors apologise for this error.