Cohort Studies

The NBER's Working Group on Cohort Studies met on May 11-12 in Cambridge. Working Group Director Dora Costa of University of California, Los Angeles organized the meeting, which honored Robert Fogel. These researchers' papers were presented and discussed:

Martha J. Bailey, University of Michigan and NBER, and Alfia Karimova and Michael J. Murto, University of Michigan

The Determinants of Life Expectancy in the 20th Century U.S.: Evidence from the LIFE-M Project

Today, differences in U.S. life expectancy are large and increasing by socio-economic status for men and women. With newly available data from the LIFE-M project, this paper uses vital statistics from North Carolina linked to the 1940 Census to shed light on how household income and educational attainment are associated with age at death for cohorts born in the early twentieth century. For men born from 1900 to 1918, Bailey, Karimova, and Murto find that higher educational attainment and household income in early adulthood are not associated with longer life. For women, however, socio-economic status in early adulthood is strongly associated with life expectancy. For women born from 1900 to 1918, one additional year of education is associated with a 0.4-year increase in longevity and an increase of household income by 10 percent is associated with an approximately 0.1-year increase in life expectancy. Interestingly, childhood income for cohorts born in the 1920s and 1930s is not correlated with life expectancy for men or women. The researchers compare their estimates to others later in the 20th century to place recent trends in longer-term context. Future work will extend this analysis to include death records from additional states.

Joseph P. Ferrie, Northwestern University and NBER

Socioeconomic Status & Child Mortality in the U.S., 1850-1940

Richard H. Steckel, Ohio State University and NBER

Height and Happiness

Dora Costa

Intergenerational Transmission of Wartime Trauma

Hoyt Bleakley, University of Michigan and NBER

The Hookworm Again

Chulhee Lee, Seoul National University

Nutrition, Health, and Human Capital Development: Evidence from South Korea, 1946-1977

The rapid economic growth of South Korea during the second half of the 20th century has resulted in an immense improvement in the standards of living of the country's population. However, neither how the living conditions in South Korea changed over time nor the major factors that produced such changes have been understood completely. Using newly collected archival data, Lee investigates how nutritional availability in two crucial periods for human growth, namely, early childhood (from conception to age 3) and adolescence (from age 12 to 16), affected the heights of South Korean conscripts born from 1946-1957. Results strongly suggest nutrition was an important determining factor of biological standards of living as indicated by adult height. Provisions of calories and protein were associated strongly with larger stature. Food availability during early childhood was more critical for human growth than nutrition in adolescence. Nutrition in growing ages also had a strong effect on educational attainment. Increased nutritional supply in adolescence mitigated the negative consequences of early-life exposure to the Korean War. Improved nutrition in early childhood and adolescence accounted for 30% to 50% of the increase in adult height (about 2 cm) that was gained between the 1951 and 1957 birth cohorts, respectively. Increased nutritional availability during early childhood explains the majority of the contribution.

Sok Chul Hong, Seoul National University

Shortened Life-Span: A Legacy of Exposure to Malaria Risk in Early Life

Hong studies historical experience to measure a long-term potential benefit of malaria eradication. Many Americans in the first half of the 19th century were exposed to high risk of malarial fevers because medical knowledge for effective prediction and prevention was inadequate. Using the sample of Union Army veterans born during the period and their lifetime records, Hong examines that the exposure to high risk of malaria at birth or in early life substantially shortened their lifespan. The legacy is estimated robust with controlling for lifetime socioeconomic and health conditions, fixed effects and selection. The negative impact on lifespan is found more substantially at veterans' younger ages, and more frequently through certain types of causes such as respiratory and digestive diseases.

Claudia Goldin, Harvard University and NBER, and Adriana Lleras-Muney, University of California, Los Angeles and NBER

XX>XY? The Changing Female Advantage in Life Expectancy (NBER Working Paper No. 24716)

Females live longer than males in most parts of the world today. Among OECD nations in recent years, the difference in life expectancy at birth is around four to six years (seven in Japan). But have women always lived so much longer than men? The answer is that they have not. Goldin and Lleras-Muney ask when and why the female advantage emerged. The researchers show that reductions in maternal mortality and fertility are not the reasons. Rather, they argue that the sharp reduction in infectious disease in the early twentieth century played a role. The primary reason is that those who survive most infectious diseases carry a health burden that affects organs, such as the heart, as well as impacting general well-being. Goldin and Lleras-Muney use new data from Massachusetts containing information on causes of death from 1887 to show that infectious diseases disproportionately affected females between the ages of 5 and 25. Increased longevity of women, therefore, occurred as the burden of infectious disease fell for all. Their explanation does not tell us why women live longer than men, but it does help understand the timing of the increase.

Maryaline Catillon, Harvard University; David M. Cutler, Harvard University and NBER; and Thomas Getzen, Temple University

Two Hundred Years of Medical Care and Health

Using two hundred years of national and Massachusetts data on medical care and health, Catillon, Cutler, and Getzen examine how central medical care is to life expectancy gains. While common theories about medical care cost growth stress growing demand, their analysis highlights the importance of supply side factors, including the major public investments in research, workforce training and hospital construction that fueled a surge in spending over the 1955-1975 span. There is a stronger case that personal medicine affected health in the second half of the twentieth century than in the preceding 150 years. Finally, the researchers consider whether medical care productivity decreases over time, and find that spending increased faster than life expectancy, although the ratio stabilized in the past two decades.

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