Multidimensional Mortality Selection: Why Individual Dimensions of Frailty Don't Act Like Frailty

• In Event: 4150 - Topics in Sociological Methodology, Session 1

Abstract

This paper demonstrates surprising consequences of partially-observed heterogeneity for estimates of disparities in mortality. As a running example, I use a specific empirical setting: At old ages, blacks outlive whites, presumably because the elderly black population was heavily selected by mortality to be highly robust. Recent research asks how multiple dimensions of heterogeneity jointly produce this “crossover,” while drawing on theoretical models of selection along just a single dimension of heterogeneity (“frailty”). I show that, when one dimension of heterogeneity is observed and another is unobserved, neither the observed nor the unobserved dimension need behave like unidimensional frailty models predict. For example, in a multidimensional model, mortality selection can increase the proportion of survivors that is disadvantaged, or “frail,” and can lead black survivors to be more frail than whites, along some dimensions of disadvantage. Transferring theoretical results about unidimensional heterogeneity to settings with both observed and unobserved heterogeneity produces misleading inferences about mortality disparities such as the black-white mortality crossover, and creates challenges for empirically testing specific selection models of the crossover.

Author

• Elizabeth Wrigley-Field, University of Minnesota