In 1931 H.W. Heinrich published the results of his famous (or infamous) studies in the book Industrial Accident Prevention: A Scientific Approach. In this text, and subsequent editions of the text, Heinrich proposed many theories regarding industrial accidents that are paradigmatic even to this day (Manuele 2011, 52). One of the more commonly known theories from Heinrich's text is his theory about causes of accidents, also known as the 88-10-2 ratio. This ratio, according to Heinrich, attributes accident proximate causes to three sources – unsafe acts, unsafe conditions, and "acts of God," with the overwhelming majority of accidents caused by unsafe acts (88%), unsafe conditions causing a much lesser amount (10%), and some accidents being essentially unpreventable "acts of God" (2%) (Heinrich 1931, 45).
In a manner of speaking, Heinrich was not really proving anything that people did not already suspect – humans are inherently involved in most accidents. In fact, considering all accidents or incidents as having a human causation is not far from the truth. After all, if no one went to work then there would be no work-related injuries or illnesses. Implicitly though humans must go to work, and in the same way they must be exposed to risk of injury or illness, particularly those risks that derive from the behavior of others.
This fact puts particular pressure on the safety professional to find effective ways of understanding and managing human behaviors. Many models, systems, and products have attempted to do this, typically under the broad category of "Behavior Based Safety," with varying degrees of success (Hale and Borys 2013, 211). However, most of the attempts to control behaviors to create safety within an organization have, ironically, missed the effect of individual factors on behavior, or they take the individual out of the context of the sociotechnical system in which they operate (Woods et. al. 2010, 21).
