Neither Leading Nor Lagging: Why Process Safety Indicators Need to Go Beyond the Time Dimension

Process Safety Indicators (PSIs) are expected to provide decision makers with synthetic and still valuable insights on the evolution of the risk systems they are supposed to control. As it is the case in almost all areas of management, the simplifications such tools may vehicle are subject to legitimate criticisms. In the field of safety, focus has been put on the ambiguities surrounding the interpretations of the lea/lag properties of PSIs. This paper ambitions to demonstrate that the discussion around the leading/lagging typology of PSIs is not only a matter of conflicting and still legitimate interpretations but the result of an ill-defined typology that does not satisfy the epistemic basic requirements of scientific typologies. In doing so, it appears necessary for the process safety community to move beyond this approach to establish a more comprehensive and less ambiguous framework for assessing the performance of a safety monitoring system.