Le jeudi 22 octobre 2009, à 13 h 30, à la salle 1240 du pavillon Alexandre-Vachon.

Cultural Imagery and Statistical Models of the Force of Mortality.
Par James Hanley, McGill University.

I will begin with the history of the term “hazard function” and its actuarial forerunner “force of mortality.” I will then describe selected artistic and scientific depictions of the force of mortality (hazard function, mortality rate), a concept that has long pre?occupied actuaries and statisticians. The “Bridge of Human Life” (Addison, 1711) provides a particularly vivid image, with the forces depicted as external. The model used by Gompertz (1825) appears to treat the forces as internal. “The Chances of Death” (Pearson, 1897) mathematically “modernizes” the medieval conception of the relation between Death and Chance by decomposing the full mortality curve into ?ve distributions along the age axis, the results of ?ve “marksmen” aiming at the human mass crossing this bridge. I will describe the imagery, critique Pearson’s statistical model, and give the Bridge of Life a modern form, illustrating it via statistical animation.?I will also describe how the epidemiologic concept of a “person-year” was viewed by an influential but little-known actuary who was a contemporary of Gompertz. This work is joint with Elizabeth Turner, a Research Fellow in Medical Statistics at the London School of Hygiene & Tropical Medicine.