It's great to see something I'm interested in, and have written about, picked up by The Economist.
It appears that's how long it's taken for Jensen's study to make it's way from a conference presentation (here are the original slides) to publication in a peer-reviewed journal, i.e. “The Digital Provide: Information (technology), market performance and welfare in the South Indian fisheries sector”, by Robert Jensen, to be published in the Quarterly Journal of Economics, August 2007.
Not to boast, but the graphics in my original post beat the text in the Economist article although that text is good:
...starting in 1997 mobile phones were introduced in Kerala. Since coverage spread gradually, this provided an ideal way to gauge the effect of mobile phones on the fishermen's behaviour, the price of fish, and the amount of waste.
As phone coverage spread between 1997 and 2000, fishermen started to buy phones and use them to call coastal markets while still at sea. (The area of coverage reaches 20-25km off the coast.) Instead of selling their fish at beach auctions, the fishermen would call around to find the best price. Dividing the coast into three regions, Mr Jensen found that the proportion of fishermen who ventured beyond their home markets to sell their catches jumped from zero to around 35% as soon as coverage became available in each region. At that point, no fish were wasted and the variation in prices fell dramatically.
Missing from the Economist article were some significant results Jensen provided in his January 2006 talk. At that time, he concluded by pointing out other impacts, beyond prices and reduced waste of fish. The advent of cellphones also led to a 6% increase in educational enrollments and a 5% increase in the probability of using of healthcare when sick. All this with no government programs and no new funding of existing programs.