Dispersive equity and social risk

Dispersive quality is concerned with the impact of life-threatening risks from alternative policy decisions on homogeneous groups in a population. It is not addressed to the disutility of various numbers of fatalities that might occur, but rather to how fatalities are distributed over the groups. Although the dispersive equality has long been recognized as an important component of some policy decisions, it has received little formal treatment within the matrix of salient factors for such decisions. The present purpose is to advance its formal development. This is done within a formulation based on probability distributions over potential fatality sets. The formulation gives rise to four distinct but not independent equity concepts: individual risk equity, group risk equity, dispersive equity, and social outcome equity. Each of these is analyzed, but special attention is given to dispersive equity. The paper also comments on relationships between total equity and its four components, and between total equity and the disutility of various numbers of fatalities.