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

Tempo effects exist in period mortality and both, conventional and tempo-adjusted life expectancy standardize for these effects, however, in a different manner. These preconditions raise the question about the purpose of period measures and how this purpose is met in the two standardization procedures. In our perspective, a period measure of mortality should reflect the actual mortality conditions of the currently living cohorts in order to allow conclusions for political or medical interventions. Using a simple population model and testing different scenarios of mortality trends we show that tempo effects can lead to severely distorted information when conventional life expectancy is used as indicator for period mortality. Tempo-adjusted life expectancy is free of providing such misleading results. From our considerations we further derive an interpretable definition for tempo-adjusted life expectancy. Such a definition is still missing and probably a major reason for the general rejection of mortality tempo-adjustment.