Testing the twin model's equal-environments assumption cuts the heritability of schooling from 34 to 9 percent.
The classic twin design reads any excess similarity between identical pairs as
genetic, which holds only if identical and fraternal pairs share their
environments to the same degree. Linking the Danish Twin Registry to the twins'
spouses and children identifies the model without assuming it, and the
assumption is rejected. Heritability falls from 34 to 9 percent of the variance
in schooling and from 60 to 16 percent in earnings. Shared family environment
accounts for 42 and 26 percent.
I study how advantages and disadvantages accumulate over a life, from the circumstances of the childhood home to how long people live. The questions are those of applied labour and public economics: schooling, pensions and retirement, labour supply, and what passes from one generation to the next. Most of the work runs on Danish administrative registers, which follow the whole population rather than a sample, and which link children to parents, workers to workplaces, and people to the care they received.
Economics of educationPensions & retirementLabour supplyIntergenerational mobilityHealth & inequality
More Findings
Three more in brief. The Research page presents
a broader selection, grouped by theme. The Projects
page presents some of the questions I am working on now.
Tutoring a few kindergartners raised reading for the whole school.
Tutoring trials usually randomise pupils within schools, which nets out any
benefit to classmates. We randomised 81 Danish schools and 2,583 kindergartners,
tutored a few in each and tested all of them. Decoding rose 0.38 standard
deviations in the pre-registered target group and 0.27 school-wide. Bounds
needing only random assignment and the test's range put the gain to
never-tutored peers at 0.19 SD or more, so evaluating tutoring within schools
understates its value two- to threefold.
The line is a lower bound, built only from random assignment and the test's score range.
Parental job loss hurts children most when it hits in infancy.
Earlier work shows that losing a job harms the children of the worker, without
saying whether the child's age matters. We use Danish plant closures, match exposed children to similar peers, and difference out the selection that does not vary with the child's age by
using parents displaced after school has ended. A job loss in a child's first two years lowers ninth-grade maths by 0.04 SD, and the families who cannot borrow their way through the shock drive the result. Job losses later in childhood do much less harm.
Dots are effects by the child's age when the parent lost their job, with 95% intervals. The grey dot is the after-school group everything is compared against.
The socioeconomic gap in lifespan is far bigger than education or income alone suggest.
Studies of inequality in lifespan usually rank people by one measure, such as
schooling or income, missing anyone high on one and low on another. We follow every Dane born in 1942 to 1944 from age 40 to 78 and use machine learning to combine education, income, wealth, occupation and IQ into one ranking. The highest-status men can expect to live 24 years longer than the lowest, and women 23 years, compared with only 9 years for either sex when ranked by education alone. Wealth is the most informative measure.
Each bar runs from the life expectancy at 40 of the lowest-ranked group to that of the highest, for each measure alone and for all combined. Right-hand numbers give the gap for men, then women.
Paul Bingley is Professor at VIVE, The Danish Center for Social Science
Research, in Copenhagen, where he works in the Health and Later Life
department. He works in applied labour and public economics, on the
economics of education, pensions and retirement, labour supply, and the
intergenerational transmission of economic outcomes, using Danish
administrative registers that cover the whole population. His research has
appeared in the Review of Economics and Statistics, the
Journal of Applied Econometrics, the Economic Journal and
the Journal of Labor Economics. Before joining VIVE he was
Professor at SFI, The Danish National Centre for Social Research.