Horizontalisation, verticalisation and longevity extension: three dimensions of the transformations of the survival curve – the case of Switzerland

Siu Lan Karen Cheung, INSERM
Fred Paccaud, Université de Lausanne

From a long time, demographers and epidemiologists have studied human survival curve which shows a “rectangularization” associated with the health transition. However, the complexity of this transformation is rarely disentangled. We propose to distinguish and measure three dimensions which are (i) the horizontalization of the survival curve due to a fall in infant mortality, (ii) the verticalization corresponding to a higher concentration of the ages at death, and (iii) the longevity extension which corresponds to a possible increase in human longevity. In this work, longevity refers to the most common length of life rather than the life expectancy at birth. Accordingly, the indicators for each dimension are built on the late mode and standard deviations from it. Using Swiss life tables since 1876-1880 and afterward, this paper documents the changes in three dimensions of the transformation of the survival curve through the 20th century.