Domino Theory — a theory of accident causation and control, developed by H.W. Heinrich, that purports that all accidents, whether in a residence or a workplace environment, are the result of a chain of events. The chain of events consists of the following sequential factors: ancestry and social environment, an individual's mistake, an unsafe action and/or physical hazard, the actual accident, and an injury as the result of the preceding factors. These factors are described as dominoes, and the removal of any one of these five factors can prevent the accident.