Conventional versus Tempo-Adjusted Life Expectancy: Which is the More Appropriate Measure for Period Mortality?

Marc Luy, Vienna Institute of Demography
Christian Wegner, Vienna Institute of Demography

This paper discusses the question: which characteristics are appropriate for a measure of period mortality should have and how are these characteristics met in conventional and tempo-adjusted life expectancy. According to our perspective, a period mortality measure should include exclusively the current mortality and should enable comparison of period-specific mortality conditions of two populations or the changes between two periods without depending on past or future trends. By using a simple population model, we show that the conventional period life expectancy does not meet these demands since it includes specific assumptions regarding future mortality, which differ between different populations. Tempo-adjusted life expectancy, however, is free of these compositional effects and thus enables the analysis and comparison of pure period-specific mortality conditions. From these considerations we also derive an interpretable definition for tempo-adjusted life expectancy. We suspect that this lack of definition could be a major reason for the general rejection of mortality tempo-adjustment.