Ages of origin and destination for a difference in life expectancy

Decomposition of a difference in life expectancies may identify ages at which the difference originates in mortality differences, or may identify ages at which the difference results in different values of person-years lived ( life table population). This study shows that the two approaches are orthogonally related to each other, and derives an origin-destination decomposition matrix in which summing in one direction produces Andreev's origin-decomposition results, while summing in the other direction produces destination-decomposition corresponding to directly-observed differences in nLx values.