Researcher David McKenzie writes in the World Bank post,
I bet that facilitating international migration is not very high up the list of interventions people think of. But it should be. In a new working paper, John Gibson and I evaluate the development impacts of New Zealand’s new seasonal worker program, the RSE. The figure below compares the per-capita income gain we estimate to those from microfinance, CCTs, and from my previous research giving grants of $100-200 to microenterprises. It is simply no contest!Double blogger (Roving Bandit and IPA) Lee notes,
The migration study wasn't randomized, but was based on 4 surveys and the next-best statistical methodology. And with impacts that big, you have quite a lot of room for bias.