Causes and consequences of early-life health

We examine the consequences of child health for economic and health outcomes in adulthood, using height as a marker of childhood health. After reviewing previous evidence, we present a conceptual framework that highlights data limitations and methodological problems that complicate the study of this topic. We then present estimates of the associations between height and a range of outcomes—including schooling, employment, earnings, health, and cognitive ability—measured in five data sets from early to late adulthood. These results indicate that, on average, taller individuals attain higher levels of education. Height is also positively associated with better economic, health, and cognitive outcomes. These associations are only partially explained by the higher average educational attainment of taller individuals. We then use data from the National Longitudinal Survey of Youth 1979 Children and Young Adults survey to document the associations between health, cognitive development, and growth in childhood. Even among children with the same mother, taller siblings score better on cognitive tests and progress through school more quickly. Part of the differences found between siblings arises from differences in their birth weights and lengths attributable to mother’s behaviors while pregnant. Taken together, these results support the hypothesis that childhood health influences health and economic status throughout adulthood.     

Income and child development

We examine how income is associated with the home environments and the cognitive and behavioral development of pre-school children using data from a birth cohort study of children born at the end of the 20th century. Lower-income 3-year-old children are more likely than wealthier children to live in homes with inadequate physical environments and to have mothers who are more likely to be stressed, depressed, harsh and unresponsive. Additionally, low income children have lower PPVT scores, more mother-reported aggressive, withdrawn, and anxious behavior problems, and also more interviewer-reported problems with behavior, than more affluent children. A key policy question is whether increases in the incomes of poor families would result in improvements in children's outcomes, at least in part through improvements in the home environment. This question is difficult to answer using observational data. However, we argue that, even under the most generous interpretation of the associations we estimate, large income transfer programs would have relatively small effects on children's cognitive and behavioral outcomes.     

Orphans in Africa: parental death,poverty, and school enrollment

We examine the impact of orphanhood on children's school enrollment in 10 sub-Saharan African countries. Although poorer children in Africa are less likely to attend school, the lower enrollment of orphans is not accounted for solely by their poverty. We find that orphans are less likely to be enrolled than are nonorphans with whom they live. Consistent with Hamilton's rule, the theory that the closeness of biological ties governs altruistic behavior, outcomes for orphans depend on the relatedness of orphans to their household heads. The lower enrollment of orphans is largely explained by the greater tendency of orphans to live with distant relatives or unrelated caregivers.     

Deterministic models for premature and postponed replacement

We examine the possibilities of premature and postponed replacement in a deterministic infinite horizon model when there is technological progress. Both revenue and operating cost deteriorate with age, but at different rates. The optimal deterministic replacement time is an implicit solution from the timing boundary obtained for the equivalent real option model using a dynamic programming framework, and then by setting the underlying volatilities equal to zero. A step change improvement characterizing technological progress in the initial operating cost level for the successor occurring during the economic lifetime of the incumbent justifies premature replacement, compared to the traditional present value approach. This finding can be extended to step change improvements in the initial revenue level for the successor and for the re-investment cost. In contrast, if the technological progress can be characterized by a constant declining rate for the initial operating cost level for the successor, then the replacement is postponed for certain parameter values. This finding can be extended to different assumed improvement rates in the initial revenue level for the successor and for the re-investment cost.     

The effects of economic and population growth on national saving and inequality

This is a progress report on ongoing research into the effects of economic and population growth on national saving rates and inequality. The theoretical basis for the investigation is the life cycle model of saving and inequality. We report evidence that is conditional on the validity of the model, as well as evidence that casts doubt on it. Using time series of cross-sectional household surveys from Taiwan, Thailand, Britain, and the United States, we show that it is possible to force a life cycle interpretation on the data on consumption, income, and saving, but that the evidence is not consistent with large rate-of-growth effects, whereby economic and population growth enhances rates of national saving. The well-established cross-country link between economic growth and saving cannot be attributed to life cycle saving, nor will changes in economic or population growth exert large effects on saving within individual countries. There is evidence in favor of the life cycle model’s prediction that within-cohort inequality of consumption and of total income—though not necessarily inequality of earnings-—should increase with the age of the cohort. Decreases in the population growth rate redistribute population toward older, more unequal, cohorts, and can increase national inequality. We provide calculations on the magnitude of these effects.     

The Impact of the AIDS Pandemic on Health Services in Africa: Evidence from Demographic and Health Surveys

We document the impact of the AIDS crisis on non-AIDS-related health services in 14 sub-Saharan African countries. Using multiple waves of Demographic and Health Surveys (DHS) for each country, we examine antenatal care, birth deliveries, and rates of immunization for children born between 1988 and 2005. We find deterioration in nearly all these dimensions of health care over this period. The most recent DHS survey for each country collected data on HIV prevalence, which allows us to examine the association between HIV burden and health care. We find that erosion of health services is the largest in regions that have developed the highest rates of HIV. Regions of countries that have light AIDS burdens have witnessed small or no declines in health care, using the measures noted above, while those regions shouldering the heaviest burdens have seen the largest erosion in non-HIV-related health services for pregnant women and children. Using semiparametric techniques, we can date the beginning of the divergence in the use of antenatal care and in children’s immunizations between high- and low-HIV regions to the mid-1990s.     

Sex differences in morbidity and mortality

Women have worse self-rated health and more hospitalization episodes than men from early adolescence to late middle age, but are less likely to die at each age. We use 14 years of data from the U.S. National Health Interview Survey to examine this paradox. Our results indicate that the difference in self-assessed health between women and men can be entirely explained by differences in the distribution of the chronic conditions they face. This is not true, however, for hospital episodes and mortality. Men with several smoking-related conditions--including cardiovascular disease and certain lung disorders--are more likely to experience hospital episodes and to die than women who suffer from the same chronic conditions, implying that men may experience more-severe forms of these conditions. While some of the difference in mortality can be explained by differences in the distribution of chronic conditions, an equally large share can be attributed to the larger adverse effects of these conditions on male mortality. The greater effects of smoking-related conditions on men's health may be due to their higher rates of smoking throughout their lives.