Overview
John Bongaarts is a demographer at the Population Council (New York). His research spans fertility measurement, tempo effects, reproductive preferences, and population policy. He is best known for co-developing (with Griffith Feeney) the Bongaarts-Feeney (B-F) tempo-adjustment framework, which corrects the period TFR for the timing distortion introduced by shifts in the mean age at childbearing, and for subsequently applying the same logic to period life expectancy. His 1999 AER paper was the first major cross-national empirical application of the B-F fertility adjustment.
Key Contributions / Features
- Bongaarts and Feeney (1998, PDR): Co-developer of the B-F tempo-adjustment formula TFR∗(t)=TFR(t)/(1−r(t)), and its parity-specific extension. This is the foundational tempo-correction procedure that Kohler and Ortega (2002) later refine to eliminate compositional bias.
- Bongaarts (1999, AER): Applied the B-F adjustment to 7 developed countries (1985–89); showed adjusted TFR averages 2.03 vs. observed 1.78 (+0.25 gap); survey evidence on expected family size supports stability of reproductive preferences near replacement; concluded fertility unlikely to fall much further.
- Bongaarts (2002, UN Expert Group Meeting): Analysis of 143 developing countries (UN 1950–2000 data); documented systematic pace deceleration as TFR falls; showed that late-transition fertility is driven by life expectancy and literacy only (GDP, urbanization, and agriculture share are insignificant); estimated that reaching near-replacement requires life expectancy ~75 + literacy ~95%; identified Fertility Stalling as a likely outcome for a nontrivial number of countries; argued that UN linear-interpolation projections produce offsetting errors at the country level but approximately correct global averages. See Fertility Stalling and Demographic Transition.
- Bongaarts and Feeney (2002, PDR) / (2003, Population Studies): Extended the tempo-correction concept to period life expectancy, proposing a tempo-adjusted e0 that generalizes to the Cross-Sectional Average Length of Life (CAL). See Tempo Effects in Mortality and Cross-Sectional Average Length of Life (CAL).
- Bongaarts (2004, Population Council Working Paper No. 192): Proposed and validated the shifting logistic model for adult mortality. Key empirical finding: the slope parameter β of the logistic force of mortality is nearly constant within populations over time (CV ≈ 2–3%), so mortality improvement manifests as a rightward shift of the senescent mortality schedule. Proposed a four-step projection method as an alternative to Lee-Carter, projecting log[α(t)] linearly; showed that Lee-Carter's assumption of time-invariant age-specific improvement rates is empirically violated and can produce implausible long-run age patterns. See Shifting Logistic Model.
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