FRED H. BIXBY
FELLOWSHIP PROGRAM
Mentor Research Interests

John Bongaarts, Ph.D.

John Bongaarts’s recent research has focused on four issues, on which he would welcome collaboration.

• The causes of variation in the HIV/AIDS epidemics in sub-Saharan Africa. HIV prevalence among adults varies among countries from <1 percent to >25 percent . Two factors—the length of the period of premarital sexual activity and male circumcision—were found to be key population risk factors, together explaining 64 percent of country variation in HIV prevalence. The countries with the largest epidemics all have high average age at marriage and long intervals of premarital sex. Frequent partner changes among the nonmarried facilitate the spread of HIV.

• Long-range trends in life expectancy in developed countries. A new decomposition method has been developed to measure the contributions of juvenile, background, and senescent mortality to life expectancy changes. Projections of these components indicate that life expectancy improvements over the next several decades will be greater than expected by most conventional projections (e.g., from the US social security administration).

• Development of a general framework for the analysis of the period quantum and tempo of life-cycle events. The existence of tempo effects is demonstrated in selected period quantum measures such as the total fertility rate and in period tempo measures such as life expectancy. Period measures derived from life tables also are found to be subject to tempo effects. Methods to remove these tempo distortions are developed and applied.

• Causes of stalling fertility declines in the developing world. Since the 1960s fertility has declined rapidly in many developing countries, and projections typically assume that this trend will continue until the replacement level is reached. However, recent evidence indicates that the average pace of decline in fertility was lower around 2000 than in the mid-1990s in sub-Saharan Africa, and about half the countries in transition in this region have stalled. A key cause of these stalls is the high and nearly stable desired family size found in many countries.

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