A New Method for Determining Why Length of Life is More Unequal in Some Populations Than in Others

Abstract

Why is there greater variability in individual longevity in some populations than in others? We propose a decomposition method designed to address that question by quantifying the effects of population differences in the spread, allocation, and timing of the principal causes of death. Applying the method to the United States and Sweden, we find that spread effects account for about two-thirds of the greater variance in age at death among American adults, meaning that two-thirds of the U.S.-Sweden difference would persist if the two countries differed only with respect to within-cause variance among adults. The remainder of the difference is due largely to allocation effects, with the greater incidence of homicides and fatal traffic accidents alone accounting for more than one-fourth of the greater variance in age at death among adults in the United States.

Hispanic-White Differences in Lifespan Variability in the United States

“…The decomposition process is developed and described in detail elsewhere (Nau and Firebaugh 2012; see also Firebaugh et al 2014). Briefly, this methodology decomposes differences in lifespan variance between two populations into the contributions of differences in (1) cause-specific variability in age at death (spread effect), (2) number of deaths attributable to each cause (allocation effect), and (3) variability in cause-specific mean age at death (timing effect).…”

“…We decompose the Hispanic-white difference in lifespan variance at ages 10 and older into the contributions of (1) cause-specific variability in age at death (spread effect), (2) the number of deaths attributable to each cause (allocation effect), and (3) variability in cause-specific mean age at death (timing effect) (Nau and Firebaugh 2012). By integrating demographic research on lifespan variability and racial/ethnic health disparities, we aim to identify which cause and age patterns of death help explain the Hispanic paradox—one of the most persistent substantive puzzles in the field of demography.…”

“…Brown et al (2012) found that nonwhites exhibit greater variability above the modal age at death relative to whites. Similarly, Nau and Firebaugh (2012:1224) examined greater lifespan variability among Americans compared with Swedes and, among Americans, identified “nontrivial differences between whites and nonwhites in the spread, allocation, and timing effects for some specific causes.” Neither of these studies, however, examined particular nonwhite subgroups of the U.S. population.…”

Inequalities of Income and Inequalities of Longevity: A Cross-Country Study

“…A further study decomposed in detail the effects of population differences in the spread, allocation, and timing of the principal causes of death in Sweden and the USA to explore variability in longevity. 36 To the best of our knowledge, ours is the first crosscountry study that estimates the effects of economic inequality on longevity inequality with a multivariate statistical model.…”

Understanding the contribution of suicide to life expectancy in South Korea

“…To reduce the number of causes, we collapsed them into nine broad categories (plus a residual category) representing key causes of death: cardiovascular diseases, cancer, chronic diseases, communicable diseases, suicide, external causes (other than suicide), mental and behavioral disorders, infant conditions, ill-defined causes, and minor causes not elsewhere classified (NEC). We adapted this scheme based on prior analyses (Acciai, Noah, and Firebaugh 2015;Firebaugh et al 2014;Nau and Firebaugh 2012), but we created separate categories for causes that are relevant to our investigation (i.e., suicide, and mental and behavioral disorders). Appendix Table A-1 describes our cause grouping in more detail.…”