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Paper · 2609.01194 · September 2026

Births are difficult to predict even with rich survey and full-population register data

Chang, Juan Perdomo, Liu, Malvina Nissim, Vecchietti, Keyon Vafa, Xinran Wang, Sayash Kapoor, Steven Skiena, Qixiang Fang, Erik-Jan Van Kesteren, Enamul Hassan, and 135 more

arXiv · PDF

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Abstract

Major life events have proven difficult to predict. Does this reflect limits of theory, data, and algorithms, or the large role of chance? We examine one outcome - having a child within three years - through a near-ideal setting for prediction: a data challenge where 147 researchers predicted births for Dutch residents aged 18-45, using survey data and full-population registers. Methods ranged from logistic regression to a large language model and transformers. Predictions were moderately accurate (best F1: register 0.59, survey 0.76); advanced models did not outperform classical ones; and the larger registers did not beat the survey. Simulating the stochastic biology of conception and pregnancy, we estimated a predictive ceiling (survey F1 ~ 0.86-0.94, register 0.88-0.96). Observed performance falls short of this ceiling, implicating imperfect data, methods, and unmodelled chance, while the ceiling itself shows that chance in reproduction alone sets a non-trivial limit on predicting individual lives.

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