The article offers an economic analysis of how people respond to terrorism. In looking at the public mood after a terrorist attack, economists can help, for it is their instinct to look at what people do, not what they say; to trust numbers, not anecdotes; and to look for clues in the inflections of mass behavior, not the hasty reflections of the mass media. Gary Becker, a Nobel laureate at the University of Chicago, and Yona Rubinstein, of Tel Aviv University, have a working paper to examine how the general public responds to the threat posed by suicide-bombers. Killing is a means of spreading fear. Terrorists introduce a small risk of violent death into humdrum daily activities. Becker and Rubinstein argue that it is not the risk of physical harm that moves people; it is the emotional disquiet. People respond to fear, not risk.