Similarly, Jenny Aker of the University of California at Berkeley analysed grain markets in Niger to see how the phasing-in of mobile-phone coverage between 2001 and 2006 affected prices.

In 2007, Indonesia started phasing in a program that gives money to its poorest residents under certain conditions, such as requiring people to keep kids in school or get regular medical care.

The phasing colours in between are blue, orange, purple and pink.