Ambient temperature and the occurrence of collective violence: a new analysis

Prevalent folklore suggests that riots tend to occur during periods of very hot weather. Baron and Ransberger examined 102 major riots in the United States between 1967 and 1971 and concluded that the frequency of collective violence and ambient temperature are curvilinearly related. The present article points out that the Baron and Ransberger analysis did not take account of the different number of days in different temperature ranges. The artifact is eliminated, and the probability of a riot, conditional upon temperature, is estimated. When this is done, the evidence strongly suggests that the conditional probability of a riot increases monotonically with temperature. Some general implications of such data analyses are discussed.