Welcome to my website. I am a lecturer in economics at the University of Bristol. I am also affiliated with the Danish Centre for Applied Social Science. I do research in applied labour economics.
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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.
Press: Stanford GSE, The Washington Post, The Seattle Times, Huffington Post, The Guardian, Quartz
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.
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).
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.
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 article is a review of the seminar paper Superstar Effect in Italian Football which was written for the seminar on sports economics at the Department of Economics, University of Copenhagen and awarded the McKinsey Award in spring 2008. Only the main findings from the seminar paper will be presented here. For details and technicalities we refer to the original seminar paper Christiansen and Sievertsen (2008), which can be dowloaded at www.econ.ku.dk/nf/superstareffect.pdf. In short, superstar economics is the branch of labour economics that deals with the phenomenon of nonlinear and highly rightskewed income distributions, that is observed in certain activities. The puzzle is, that the most talented individuals in these activities can obtain extremely high salaries compared to their colleagues, even though they are only marginally more talented. Theoretical explanations of the puzzle are reviewed and the superstar phenomenon is analysed empirically on Italian football, where a significant superstar effect is found.
Abstract: Using firm-level survey- and register-data for both Sweden and Denmark we show systematic mis-measurement in both vacancy measures. While the register-based measure on the aggregate constitutes a quarter of the survey-based measure, the latter is not a super-set of the former. To obtain the full set of unique vacancies in these two databases, the number of survey vacancies should be multiplied by approximately 1.2. Importantly, this adjustment factor varies over time and across firm characteristics. Our findings have implications for both the search-matching literature and policy analysis based on vacancy measures: Observed changes in vacancies can be an outcome of changes in mis-measurement, and are not necessarily changes in the actual number of vacancies.
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.