“The trouble with living on two dollars a day is that you don’t actually get two dollars a day. One day you might get five, then nothing for the next three days. Income is unpredictable. Outgoings, too, are irregular. Emergencies crop up. Under the circumstances, the most basic financial product, such as an easy-access savings account, would be invaluable.

“We know about this thanks to a new study by Daryl Collins, Jonathan Morduch, Stuart Rutherford and Orlanda Ruthven, detailed in their forthcoming book, Portfolios of the Poor.”

This from Tim Harford over at the FT.  Read the rest of his column here.