‘Big data’ from social media, elsewhere online redefines trend-watching

From a trading desk in London, Paul Hawtin monitors the fire hose of more than 340 million Twitter posts flying around the world each day to try to assess the collective mood of the populace.

The computer program he uses generates a global sentiment score from 1 to 50 based on how pessimistic or optimistic people seem to be from their online conversations. Hawtin, chief executive of Derwent Capital…