Williams, a sociologist, had always based his research on data gathered by clipboard-wielding graduate students. But when people know they're being watched, they change their answers with startling regularity, so much so that the behavior has a name, the Hawthorne effect (for the factory in Chicago where it was first observed). Four years ago, just before the economy imploded, Williams and his colleagues found a way to counteract the Hawthorne effect. After asking permission from the game's manufacturer, Williams was able to access 4.5 terabytes of player data from the "massively multiplayer" online game EverQuest II. The data set was enormous; it chronicled every action, exchange and decision made by nearly five million players. By comparison, the General Social Survey, the benchmark for sociological research in the U.S., consists of some 800 questions answered by about 5,000 people. The game data also drew on behavior that was, at least from the perspective of the players, unobserved.