Potential demography: a second look.

"In the late forties Hersch (1944) and Mentha (1948) introduced, respectively, the concepts of 'potential years of life' (PYL) and 'potential years of life lost' (PYLL).... Our objectives are: (a) to draw attention to Hersch's concept of potential years of life (PYL) and to illustrate its usefulness; (b) to define and illustrate three different manners of computing PYLL and to recommend one that is simple, intuitively acceptable and reasonably accurate; (c) to propose some further indicators that can be derived from PYL, PYLL and the relations between them; and (d) to discuss briefly the assumptions underlying the calculation of PYL and PYLL, and in particular those assumptions that are made in the attribution of loss in potential years of life to specific risk factors." (SUMMARY IN FRE) excerpt