From a post by David Aronson on the Congo Resources blog:
“One thought occurred to me: Cell phone minutes. Cell phones are pretty ubiquitous, at least in town. Most people don’t have monthly plans. Instead, they buy cell phone minutes in increments of one to five dollars at a time. When people aren’t doing so well, they purchase fewer of those minutes. When they’re flush, they purchase more. As a proxy for economic trends, then, minutes have several advantages. They aren’t a requirement of life, like rent or food. But neither are they a lagging indicator, the result of pre-existing contracts and commitments, in the way that labor costs might be. Instead, they reflect how well people feel they are doing at the very moment the minutes are purchased. They are, to use an economic term I probably have no business using, highly elastic.”