Compression of mortality: a cohort-oriented approach

Dalkhat M. Ediev, Vienna Institute of Demography

The rapid increase of human longevity has brought up important questions about what implications it may have for the variability of age at death. Earlier works reported evidence of a historical trend of mortality compression. However, the period life table model, which is widely used to address mortality compression, produces an artificially compressed picture of mortality as a built-in feature of the model. We base our study on examining the durations of exposure of birth cohorts (also as compared to period mortality schedules) to selected levels of mortality observed at old age. We also address the problem in a more conventional fashion, by examining the distribution of ages at death (in period tables and cohorts) above and below the mode. Overall, mortality has been significantly de-compressing already since the 1960s. This finding contradicts with most previously reported results. The decompression of old-age mortality may indicate further optimistic prospects of ever-decreasing mortality. Mortality may well not be concentrated in the future within a narrow age interval but more dispersed along age groups, though at ever later ages on average.