The study in one sentence and one chart
We show that birthweight is associated with the schooling outcomes of the next generation for both mothers and fathers and that this association is considerably stronger than partial estimates suggest.

Abstract: This paper documents a strong relationship between birth endowments of parents and the cognitive development of their children. The association between maternal birth weight and child school test scores corresponds to 80 percent of the association between the child's own birth weight and test scores (both in univariate and multivariate settings). We find a strong relationship, even when controlling for family differences, by looking at birth weight variation between sisters and the test score outcomes of their children, and when controlling for parental education and economic resources. Child test scores are also strongly related to paternal birth weight. To assess external validity, we replicate recent results from the US on the relationship between child birth weight and test scores. Our intergenerational results suggest that inequality in birth endowments may be important for inequality in key outcomes of the next generation.

The study in one sentence and one chart
We show student segregation in Danish high schools increased after these schools became self-governed and activity based funded, but only in areas with a high concentration of high schools.

The study in one sentence and one chart
We exploit that top-earnings are approximately Pareto distributed to propose a way to summarize top-earnings gender disparities and provide a tax-interpretation, where the gender gap corresponds to the overall tax level and the glass-ceiling coefficient to the tax progressivity.

Abstract: We exploit that top-earnings are approximately Pareto distributed to propose a way to summarize top-earnings gender disparities. The approach has at least two advantages: First, we can summarize the gender disparities with two statistics only: a top-earnings gender gap and a glass-ceiling coefficient. Second, the approach provides an intuitive tax interpretation of the gender disparities, where the gender gap corresponds to the overall tax level and the glass-ceiling coefficient to the tax progressivity. The tax interpretation highlights that the two disparity statistics are not necessarily related. We illustrate this using Danish administrative data for the period 1980-2013.

The study in one sentence and one chart
We find that students compensate for a shock to a high-stakes GPA by adjusting their performance in subsequent assessment, which has long-run effects on their human capital accummulation.

Abstract: High-stakes exams provide students with incentives to perform well. This paper uses a reform-induced recoding of grades from completed exams, which caused variation in high school students’ grade point average (GPA), to identify students’ behavioral responses to changes in high-stakes grades. The results show that students who were downgraded by the recoding performed better on subsequent assessments and worked less for pay during high school. Students with downgraded grades were also somewhat more likely to enroll in college. As the recoding did not convey information on academic performance, these results emphasize that changes in incentives are important in understanding students’ responses to high-stakes grades. There is no evidence that the recoding algorithm predicts outcomes for non-affected cohorts.

The study in one sentence and one chart
We compare the relationship between the Strength Difficulties Questionnaire and the performance in standardized tests across respondent type and child age.

Abstract: Exploiting nation-wide data from the Danish National Birth Cohort, we show that children’s emotional and behavioral problems measured by the Strengths and Difficulties Questionnaire (SDQ) are closely related to their performance in standardized academic tests for reading and mathematics in sixth grade. The relationship is remarkably linear across the entire distribution for both the total difficulties score and subscale scores of the SDQ; higher scores on the SDQ (more problems) are related to worse performance in academic tests. We assess the similarity across respondent type; parent (child age 7 and 11), teacher (child age 11) and self-reported scores (child age 11), and find that teacher and parent reported scores have very similar slopes in the SDQ–test score relationship, while the child reported SDQ in relation to the academic test performance has a flatter slope.

The study in one sentence and one chart
Compared to children born in December, January-born children are older at school entry and have fewer mother-reported difficulties at age 7 and 11y.

Abstract: Using linked Danish survey and register data, we estimate the causal effect of age at kindergarten entry on mental health. Danish children are supposed to enter kindergarten in the calendar year in which they turn 6 years. In a "fuzzy" regression-discontinuity design based on this rule and exact dates of birth, we find that a 1-year delay in kindergarten entry dramatically reduces inattention/hyperactivity at age 7 (effect size = –0.73), a measure of self-regulation with strong negative links to student achievement. The effect is primarily identified for girls but persists at age 11.

The study in one sentence and one chart
Exploiting the Danish roll-out of policies, we find that children who were discharged from hospital on the day of birth have worse health and schooling outcomes later in life.

Abstract: Exploiting the Danish roll-out of same-day discharge policies after uncomplicated births, we find that treated newborns have a higher probability of hospital readmission in the first month after birth. While these short-run effects may indicate substitution of hospital stays with readmissions, we also find that—in the longer run—a same-day discharge decreases children's ninth grade GPA. This effect is driven by children and mothers, who prior to the policy change would have been least likely to experience a same-day discharge. Using administrative and survey data to assess potential mechanisms, we show that a same-day discharge impacts those parents’ health investments and their children's medium-run health. Our findings point to important negative effects of policies that expand same-day discharge policies to broad populations of mothers and children.

The study in one sentence and one chart
Exploiting quasi-random variation in the timing of tests, we show that children's performance in standardized tests is affected by time of the day they take the test.

Abstract
Using test data for all children attending Danish public schools between school years 2009/10 and 2012/13, we examine how the time of the test affects performance. Test time is determined by the weekly class schedule and computer availability at the school. We find that, for every hour later in the day, test performance decreases by 0.9% of an SD (95% CI, 0.7–1.0%). However, a 20- to 30-minute break improves average test performance by 1.7% of an SD (95% CI, 1.2–2.2%). These findings have two important policy implications: First, cognitive fatigue should be taken into consideration when deciding on the length of the school day and the frequency and duration of breaks throughout the day. Second, school accountability systems should control for the influence of external factors on test scores.

Extra material: Break data; Break do-file (for Stata).
Press: Scientific American, Forbes, Huffington Post, Phys.org, Harvard Business Review, BBC (radio show), Quartz , Daily Mail, NyMag, Spiegel, Videnskab.dk, Politiken

The study in one sentence and one chart
Exploiting a nurse-strike in 2008we find that reduced professional health care around birth is related to higher demand for postnatal health care.

Abstract: Care around birth may impact child and mother health and parental health investments. We exploit the 2008 national strike among Danish nurses to identify the effects of care around birth on infant and mother health (proxied by health care usage) and maternal investments in the health of their newborns. We use administrative data from the population register on 39,810 Danish births in the years 2007–2010 and complementary survey and municipal administrative data on 8288 births in the years 2007–2009 in a differences-in-differences framework. We show that the strike reduced the number of mothers' prenatal midwife consultations, their length of hospital stay at birth, and the number of home visits by trained nurses after hospital discharge. We find that this reduction in care around birth increased the number of child and mother general practitioner (GP) contacts in the first month. As we do not find strong effects of strike exposure on infant and mother GP contacts in the longer run, this result suggests that parents substitute one type of care for another. While we lack power to identify the effects of care around birth on hospital readmissions and diagnoses, our results for maternal health investments indicate that strike-exposed mothers—especially those who lacked postnatal early home visits—are less likely to exclusively breastfeed their child at four months. Thus reduced care around birth may have persistent effects on treated children through its impact on parental investments.

The study in one sentence and one chart
Worse local labor market conditions causes students to advance their enrollment, and consequently their completion, of additional schooling.

Abstract: Using Danish administrative data on all high school graduates from 1984 to 1992, I show that local unemployment has both a short- and a long-run effect on school enrollment and completion. The short-run effect causes students to advance their enrollment, and consequently their completion, of additional schooling. The long-run effect causes students who would otherwise never have enrolled to enroll and complete schooling. The effects are strongest for children of parents with no higher education.

Abstract: This paper contributes to the debate on intergenerational mobility in the U.S. and Denmark by linking parental resources to differentials in cognitive development as they develop through primary and lower secondary school in each country. Using U.S. survey data and Danish register data, we observe a socio-economic gradient along the entire test score distribution in both countries, but the gradient is always largest in the U.S. The test-score difference between the above and below median household income groups at school entry is about 20 percent larger in the U.S. compared with Denmark. Our findings show that a substantial socio-economic test-score gradient is present even in a Scandinavian welfare state with universal child policies. However, in light of the recent debate on similarities in intergenerational mobility between Denmark and the U.S., it is important to note that the socio-economic gradient in test-scores is smaller in Denmark compared with the U.S.