Henrik Daae Zachrisson

• Lyhmann, Ingvild; Widding-Havnerås, Tarjei; Markussen, Simen; Zachrisson, Henrik Daae; Elwert, Felix & Chaulagain, Ashmita [Show all 9 contributors for this article] (2026). Effect of pharmacological treatment of attention-deficit hyperactivity disorder on academic performance: registry-based population study. British Journal of Psychiatry. ISSN 0007-1250. p. 1–8. doi: 10.1192/bjp.2026.10754. Full text in Research Archive Show summary

  Background Attention-deficit hyperactivity disorder (ADHD) is associated with high risks of adverse academic outcomes. A major motivation for initiating pharmacological treatment of ADHD is to mitigate these risks; however, the evidence regarding its long-term effects is inconclusive. Aims Our objective was to investigate the long-term causal effects of pharmacological treatment of ADHD on school grades in Norwegian children and adolescents. Method We analysed individual-level registry data of all Norwegians aged 5–15 years in 2009–2011 who were diagnosed with ADHD during this period (n = 6255). Treatment was measured as cumulative ADHD medication prescriptions from time of diagnosis to graduation from mandatory schooling (tenth grade). Outcomes included final grades in nine main school subjects, grade point average and non-assessment (exemption, no basis for assessment). We estimated ordinary least squares (OLS) and instrumental variable models. By exploiting naturally occurring variation in treatment practices, instrumental variable analysis can address residual confounding and estimate causal effects for patients ‘on the margin of treatment’, i.e. those prone to varying treatment practices. Results OLS analysis indicated that pharmacological treatment for ADHD was associated with slightly improved grade point average (0.05, 95% CI 0.02–0.09; grade point average s.d. 0.94). Instrumental variable analysis indicated no causal effect of pharmacological treatment on grade point average (−0.01, Anderson−Rubin 95% CI −1.13 to 0.15), individual school subjects or non-assessment. Conclusions For children and adolescents on the margin of pharmacological treatment for ADHD, we found no causal effect of pharmacological treatment on any of our measures of academic performance. Although further research is needed, this finding should be considered in the context of clinical decision-making and treatment planning.

• Widding-Havnerås, Tarjei; Demange, Perline Aline Delle; Zachrisson, Henrik Daae; Borgen, Nicolai; Ystrøm, Eivind & Elwert, Felix (2026). Estimating returns to education using the genetic lottery. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 123(15), p. 1–10. doi: 10.1073/pnas.2537049123. Full text in Research Archive Show summary

  Does more schooling cause higher lifetime earnings? Social scientists have long sought to determine the economic returns to schooling given its importance to individual life chances and public policy. Prior estimates are limited by unobserved confounding in observational studies and the focus of popular quasi-experimental studies on increases in schooling at only one particular age. Genotyped data offer an opportunity to address unobserved confounding and to estimate the returns to an additional year of schooling at any age by using quasi-randomly assigned genetic variants related to education as instrumental variables [Mendelian randomization (MR)]. We analyze comprehensive Norwegian population registries with career-long earnings data and genotyped data from the Norwegian Mother, Father and Child Cohort Study (MoBa). We employ three identification strategies for triangulation: ordinary least squares (OLS) with covariate-adjustment, sibling and twin fixed-effects models, and MR. Estimated returns to schooling are 8.0% in MR (N = 109,800) and 6.3% in sibling-MR (N = 18,666). Extensive sensitivity analyses suggest that MR results are robust even to large potential violations of MR assumptions, including pleiotropy. MR estimates somewhat higher returns than OLS for the full population (5.9%, N = 1,255,604) and fixed-effects models for siblings (5.3%, N = 966,976) or monozygotic twins (3.2%, N = 2,630). The estimated internal rate of return to schooling exceeds opportunity costs of education as proxied by the market interest rate. The lifetime returns to schooling are positive and substantial across all models.

• Inal, Gülbin Sengul; Borgen, Nicolai T.; Dearing, Eric Curtis & Zachrisson, Henrik Daae (2025). The double jeopardy of low family income and negative emotionality: The family stress model revisited. Development and Psychopathology. ISSN 0954-5794. p. 1–18. doi: 10.1017/S0954579424000373. Full text in Research Archive Show summary

  The family stress model has, for decades, guided empirical work linking poverty with increased risk of child social-emotional dysfunction. The present study extends this line of work by examining whether child negative emotionality moderates associations between family income, family stress (maternal distress, parental locus of control, and relationship dissatisfaction), and later externalizing and internalizing behavior problems. In a longitudinal population-based sample (n ~ 80,000) of Norwegian children followed from birth through age five (The Norwegian Mother, Father, and Child Cohort Study; MoBa), we examined whether high (vs. moderate or low) negative emotionality families would display: (a) compounding stress (i.e., particularly strong associations between low family income and family stress), (b) diathesis-stress (i.e., particularly strong associations between family stress and behavior problems), or (c) double jeopardy (i.e., both compounding stress and diathesis-stress moderating effects). Negative emotionality significantly moderated the association between family income and behavior problems in a manner most consistent with double jeopardy. As a result, compared with children with moderate/low negative emotionality, the family income-behavior problems association was two to three times larger for those with higher negative emotionality. These findings underscore the active role children may play in family processes that link low family income with behavior problems.

• Borgen, Nicolai Topstad & Zachrisson, Henrik Daae (2025). How neighborhood effects vary by achievement level. European Sociological Review. ISSN 0266-7215. doi: 10.31235/osf.io/x2hym. Full text in Research Archive Show summary

  After long-standing calls for research into “for whom” neighborhood matters, the literature has recently gained traction, focusing on background characteristics such as gender, race, and socioeconomic background. However, there is still scarce and only indirect evidence on whether neighborhood effects vary by children’s academic proneness. In this paper, we combine the Neighborhood Choice Model with quantile regressions to investigate whether neighborhood effects vary by children’s achievement level. Using Norwegian register data, we demonstrate heterogeneity in the effects of neighborhood deprivation as a function of students’ proneness to academic achievement. Students at the very lowest and highest levels of academic achievement are the least affected by neighborhood disadvantage, while those with achievement below average—but not at the lowest end—are most strongly affected. Moreover, while girls are less affected than boys, and children from less educated and affluent families are more affected by neighborhood disadvantage than their more privileged peers, the effects of these observed moderators are considerably smaller than the heterogeneity observed as a function of academic proneness. Overall, our use of quantile regressions opens up new venues for understanding “for whom” neighborhoods matter, with individual-level academic vulnerability and strengths being an influential source of neighborhood effects variation.

• Inal, Gülbin Sengul; Borgen, Nicolai Topstad; Skopek, Jan; Nærde, Ane & Zachrisson, Henrik Daae (2025). Maternal education, early language skills, and mother–child interactions across three welfare states. Journal of Marriage and Family. ISSN 0022-2445. 87(4), p. 1549–1570. doi: 10.1111/jomf.13087. Full text in Research Archive Show summary

  Objective This study aims to examine the extent to which maternal education-related disparities in child language development in preschool years are mediated by differences in mother–child interaction quality, and whether this mediation varies across different sociopolitical contexts: the U.S., Germany, and Norway. Background Socioeconomic disparities in language development have prompted research to investigate mechanisms underlying early language disparities. Moreover, welfare states structure the opportunities available and accessible to all parents and children. Thus, it becomes crucial to understand how family mechanisms differ across different sociopolitical contexts. Method The study uses data from the U.S., Germany, and Norway with comparable measures based on ex-post harmonization across early childhood to examine cross-country differences in whether the association between maternal education and language development was explained by the observed quality of mother–child interactions. Results Mother–child interactions partly mediate the association between maternal education and language skills, with similar indirect effects in all three countries. Because maternal education is more strongly associated with language skills in the U.S. compared to Germany and Norway, mother–child interactions explain a considerably lower proportion of the total effect in the U.S. Conclusion Mother–child interactions play a consistent role in language disparities regardless of sociopolitical context, suggesting that the broader sociopolitical context does not influence these micro-processes. Other factors related to the sociopolitical context seem to cause larger education-related gaps in language skills in the U.S. compared to Germany and Norway.

• Borgen, Solveig Topstad; Borgen, Nicolai T. & Zachrisson, Henrik Daae (2025). Ethnic minorities in disadvantaged neighborhoods: Differential effects on educational outcomes. Social Science Research. ISSN 0049-089X. 127. doi: 10.1016/j.ssresearch.2025.103152. Full text in Research Archive Show summary

  The recent influx of immigrants to affluent Western societies over past decades has spurred a massive political and academic interest in immigrant integration. In this paper, we explore the role of neighborhoods in this integration process using population-wide Norwegian register data. Our findings reveal considerable socioeconomic disparities in neighborhood conditions among children from different immigrant backgrounds, underscoring the unequal opportunities experienced by these groups. While children of immigrants from high-achieving groups tend to reside in more privileged areas, those who face educational challenges are often concentrated in the most deprived neighborhoods. Furthermore, we find that the influence of socioeconomically disadvantaged neighborhoods on 5th-grade school achievements varies across children with origins from different regions. Specifically, children with parents originating from Asia, Sub-Saharan Africa, and the MENA region are less affected by neighborhood disadvantage compared to natives and other immigrant-origin groups. Supplementary analyses suggest that this resilience to neighborhood disadvantage is partly explained by the buffering effects of co-ethnic communities. In conclusion, the findings of this paper underscore that a nuanced understanding of the role of neighborhoods is needed to decipher social inequalities between not just children of immigrants and native-born children but also between immigrant descendants of different origins.

• Halvorsen, Ola Krogh; Biele, Guido; Zachrisson, Henrik Daae & Brandlistuen, Ragnhild Eek (2025). Socioeconomic disparities in special education provision. European Journal of Special Needs Education. ISSN 0885-6257. 40(6), p. 1110–1128. doi: 10.1080/08856257.2025.2478336. Full text in Research Archive Show summary

  A central aim of educational policies is to ensure equal opportunities for all students. We examine to what extent special education provision varies with socioeconomic status. Using the Norwegian Mother, Father, and Child Cohort Study (MoBa) linked with registry data, we follow children aged 8 (N = 43,282) and 14 (N = 17,482) to examine whether socioeconomic differences in the provision of special education can be accounted for by differences in the need for special education. The analysis applies logistic regression models to estimate adjusted risk ratios based on marginal effects. Results show that students with parents with fewer years of education are more likely to receive special education but that this association diminishes after adjusting for psychiatric diagnoses and school performance. A subgroup analysis of students with ADHD, who have a high propensity for receiving special education, supports these findings.

• Borgen, Nicolai Topstad; Zachrisson, Henrik Daae; Lyngstad, Torkild Hovde; Cheesman, Rosa Catherine Gillespie & Ystrøm, Eivind (2024). For whom neighborhoods matter: Heterogeneous effects of socioeconomic neighborhood composition on child achievement. SocArXiv. doi: 10.31235/osf.io/fst58. Full text in Research Archive
• Aleman, Jose Manuel Arencibia; Sandsør, Astrid Marie Jorde; Zachrisson, Henrik Daae & Blömeke, Sigrid (2024). Teacher-assigned grades and external exams: sources of discrepancy. Assessment in Education: Principles, Policy & Practice. ISSN 0969-594X. 31(2), p. 94–115. doi: 10.1080/0969594X.2024.2338764. Full text in Research Archive Show summary

  Modest correlations between teacher-assigned grades and external assessments of academic achievement (r = .40–.60) have led many educational stakeholders to deem grades subjective and unreliable. However, theoretical and methodological challenges, such as construct misalignment, data unavailability and sample unrepresentativeness, limit the generalisability of previous findings. We overcome these challenges by exploiting rich, population-wide data from the National Registries in Norway (n = 511,858), where state regulations require close construct alignment between grades and external exams. Correlations between lower-secondary education final grades and external exam results (r = .64–.86) suggest that grades are better measures of academic achievement than previously acknowledged. Dominance analyses and multivariate regression analyses indicate that external exam results are the best predictor of grades in the same subject. However, our results also indicate that state regulations and quality assurance systems cannot completely eradicate potential sources of discrepancy.

• Dearing, Eric Curtis; Bustamante, Andres S.; Zachrisson, Henrik Daae & Vandell, Deborah Lowe (2024). Accumulation of Opportunities Predicts the Educational Attainment and Adulthood Earnings of Children Born Into Low- Versus Higher-Income Households. Educational Researcher. ISSN 0013-189X. p. 1–12. doi: 10.3102/0013189X241283456. Full text in Research Archive Show summary

  Scholars theorize that “opportunity gaps” drive achievement disparities between children born into poverty versus affluence. In a 26-year longitudinal study (N = 814), we examine (a) economic disparity in children’s accumulation of opportunities—from birth through high school—at home, childcare, school, afterschool, and in the neighborhood; (b) the extent to which opportunity is linked with educational attainment and earnings in early adulthood; and (c) whether opportunity is most strongly associated with these adult outcomes for children from low-income households. We document large opportunity gaps between children from low- versus higher-income households. These opportunity gaps are strongly linked with educational attainment and earnings, particularly for low-income children, helping explain why household income in early childhood predicts these outcomes in adulthood.

• Ribeiro, Luisa Jacinta Feio Antunes; Donolato, Enrica; Aguiar, Cecília; Correia, Nadine & Zachrisson, Henrik Daae (2023). Concurrent and Longitudinal Associations Between Parent Math Support in Early Childhood and Math Skills: A Meta-Analytic Study. Journal of Cognition and Development. ISSN 1524-8372. doi: 10.1080/15248372.2023.2248259. Full text in Research Archive
• Widding-Havnerås, Tarjei; Zachrisson, Henrik Daae; Markussen, Simen; Elwert, Felix; Lyhmann, Ingvild & Chaulagain, Ashmita [Show all 10 contributors for this article] (2023). Effect of Pharmacological Treatment of Attention-Deficit/Hyperactivity Disorder on Criminality. Journal of the American Academy of Child and Adolescent Psychiatry. ISSN 0890-8567. 63(4), p. 1–10. doi: 10.1016/j.jaac.2023.05.025. Full text in Research Archive Show summary

  Objective: Criminality rates are higher among persons with attention-deficit/hyperactivity disorder (ADHD), and evidence that medication reduces crime is limited. Medication rates between clinics vary widely even within universal health care systems, partly because of providers’ treatment preferences. We used this variation to estimate causal effects of pharmacological treatment of ADHD on 4-year criminal outcomes. Method: We used Norwegian population-level registry data to identify all unique patients aged 10 to 18 years diagnosed with ADHD between 2009 and 2011 (n = 5,624), their use of ADHD medication, and subsequent criminal charges. An instrumental variable design, exploiting variation in provider preference for ADHD medication between clinics, was used to identify causal effects of ADHD medication on crime among patients on the margin of treatment, that is, patients who receive treatment because of their provider’s preference. Results: Criminality was higher in patients with ADHD relative to the general population. Medication preference varied between clinics and strongly affected patients’ treatment. Instrumental variable analyses supported a protective effect of pharmacological treatment on violence-related and public-order−related charges with numbers needed to treat of 14 and 8, respectively. There was no evidence for effects on drug-, traffic-, sexual-, or property-related charges. Conclusion: This is the first study to demonstrate causal effects of pharmacological treatment of ADHD on some types of crimes in a population-based natural experiment. Pharmacological treatment of ADHD reduced crime related to impulsive-reactive behavior in patients with ADHD on the margin of treatment. No effects were found on crimes requiring criminal intent, conspiracy, and planning.

• Widding-Havnerås, Tarjei; Elwert, Felix; Markussen, Simen; Zachrisson, Henrik Daae; Lyhmann, Ingvild & Chaulagain, Ashmita [Show all 10 contributors for this article] (2023). Effect of ADHD medication on risk of injuries: a preference-based instrumental variable analysis. European Child and Adolescent Psychiatry. ISSN 1018-8827. 33. doi: 10.1007/s00787-023-02294-6. Full text in Research Archive Show summary

  ADHD is associated with an increased risk of injury. Causal evidence for effects of pharmacological treatment on injuries is scarce. We estimated effects of ADHD medication on injuries using variation in provider preference as an instrumental variable (IV). Using Norwegian registry data, we followed 8051 patients who were diagnosed with ADHD aged 5 to 18 between 2009 and 2011 and recorded their ADHD medication and injuries treated in emergency rooms and emergency wards up to 4 years after diagnosis. Persons with ADHD had an increased risk of injuries compared to the general population (RR 1.35; 95% CI: 1.30–1.39), with higher risk in females (RR 1.47; 95% CI: 1.38–1.56) than males (RR 1.23; 95% CI: 1.18–1.28). The between-clinics variation in provider preference for ADHD medication was large and had a considerable impact on patients’ treatment status. There was no causal evidence for protective effects of pharmacological treatment on injuries overall for young individuals with ADHD characterized by milder or atypical symptoms. However, there was an apparent effect of pharmacological treatment over time on the risk of injuries treated at emergency wards in this patient group.

• Yu, Baeksan; Zachrisson, Henrik Daae; Cheesman, Rosa Catherine Gillespie; Ystrøm, Eivind & Nes, Ragnhild Bang (2023). Boys with overweight status lagged behind girls with overweight status in reading: evidence from mendelian randomization. Journal of Clinical Epidemiology. ISSN 0895-4356. 159, p. 199–205. doi: 10.1016/j.jclinepi.2023.05.001. Full text in Research Archive Show summary

  Objectives We investigated the relationship between childhood weight status and academic achievement across sexes and different school subjects in Norway. Study Design and Setting We used data from the Norwegian Mother, Father and Child Cohort Study (MoBa), which includes genetic data (N = 13,648, 8-year-old children). We employed within-family mendelian randomization, using a body mass index (BMI) polygenic risk score as an instrument to address unobserved heterogeneity. Results Contrary to most previous findings, we observed that overweight status (including obesity) has more detrimental effects on reading achievement in boys than in girls; the test scores of boys with overweight were about a standard deviation lower than those of normal weight boys, and the negative effects on reading achievement became stronger in the later grade. Conclusion Previous obesity prevention studies have mainly targeted girls, based on the assumption that the obesity penalty is greater for girls. Our findings highlight that particular attention to boys with overweight may help reduce the existing gender gap in academic achievement.

• Alexandersen, Nina; Zachrisson, Henrik Daae; Røysamb, Espen; Wilhelmsen, Tiril; Wang, Mari Vaage & Brandlistuen, Ragnhild Eek (2023). Preschool structural quality and student–teacher closeness are related to children's adjustment: sibling-informed design. Early Childhood Research Quarterly. ISSN 0885-2006. 66, p. 48–60. doi: 10.1016/j.ecresq.2023.08.009. Full text in Research Archive Show summary

  This study aims at examining whether children's adjustment, social play behavior and Early Childhood Education and Care (ECEC) program-liking in universal ECEC are associated with the quality of student–teacher relationships and structural quality features of the classrooms they attend. The sample includes 7,436 5-year-old children (50% girls) and 195 sibling pairs (48% girls) participating in the nationwide Norwegian Mother, Father and Child Cohort Study (MoBa). Three sets of findings are presented. First, student–teacher closeness is associated with children's adjustment (β = .47; SE = .01), ECEC liking (β = .14; SE = .02) and social play behavior (β = .06; SE = .02) in the between-child analysis. Second, associations of student–teacher closeness with children's adjustment and ECEC liking are evident even after accounting for all confounders shared by siblings in the within-family analysis (sibling fixed effects). Third, structural quality indicators are related to the children's outcomes primarily via quality of student–teacher relationships.

• Constantinou, Andrea; Soest, Tilmann Martin von; Zachrisson, Henrik Daae; Torvik, Fartein Ask; Cheesman, Rosa Catherine Gillespie & Ystrøm, Eivind (2023). Childhood personality and academic performance: A sibling fixed-effects study. Journal of Personality. ISSN 0022-3506. p. 1–13. doi: 10.1111/jopy.12900. Full text in Research Archive Show summary

  Objective: This study investigated the associations between personality traits at age 8 and academic performance between ages 10 and 14, controlling for family confounds. Background: Many studies have shown links between children’s personality traits and their school performance. However, we lack evidence on whether these associations remain after genetic and environmental confounders are accounted for. Method: Sibling data from the Norwegian Mother and Child Cohort Study (MoBa) were used (n = 9701). First, we estimated the overall associations be- tween Big Five personality traits and academic performance, including literacy, numeracy, and foreign language. Second, we added sibling fixed effects to remove unmeasured confounders shared by siblings as well as rating bias. Results: Openness to Experience (between-person β = 0.22 [95% CI: 0.21–0.24]) and Conscientiousness (between-person β = 0.18 [95% CI 0.16–0.20]) were most strongly related to educational performance. Agreeableness (between-per- son β = 0.06 [95% CI −0.08–0.04]) and Extraversion (between-person β = 0.02 [95% CI 0.00–0.04]) showed small associations with educational performance. Neuroticism had a moderate negative association (between-person β = −0.14 [95% CI −0.15–0.11]). All associations between personality and performance were ro- bust to confounding: the within-family estimates from sibling fixed-effects mod- els overlapped with the between-person effects. Finally, childhood personality was equally predictive of educational performance across ages and genders. Conclusions: Although family background is influential for academic achieve- ment, it does not confound associations with personality. Childhood personal- ity traits reflect unbiased and consistent individual differences in educational potential.

• Zachrisson, Henrik Daae; Dearing, Eric Curtis; Borgen, Nicolai Topstad; Sandsør, Astrid Marie Jorde & Karoly, Lynn (2023). Universal Early Childhood Education and Care for Toddlers and Achievement Outcomes in Middle Childhood. Journal of Research on Educational Effectiveness. ISSN 1934-5747. 17(2), p. 259–287. doi: 10.1080/19345747.2023.2187325. Full text in Research Archive Show summary

  We estimated the effects of Norway’s universal ECEC program—expanding access to 1- and 2-year-olds starting in the early 2000s—on standardized math and achievement tests in 5th grade (age 10) using a population-based survey sample (Norwegian Mother, Father, and Child Cohort Study, MoBa, n = 102,352), linked with national administrative records of child achievement test scores. We used two methods to test the effects of attending ECEC: fixed-effects and instrumental variable regressions. Although both approaches found small and mostly insignificant main effects, the effect of ECEC is consistently stronger for children from families with low parental education. The fixed-effects analyses showed that ECEC reduced inequalities in achievement across levels of parental education by about 10% while the instrumental variable analyses, using variation in ECEC induced by the expansion, showed reduction of about 50%. These results suggest that expanding access to ECEC for toddlers has the potential to reduce achievement inequality.

• Sandsør, Astrid Marie Jorde; Zachrisson, Henrik Daae; Karoly, Lynn & Dearing, Eric Curtis (2023). The Widening Achievement Gap Between Rich and Poor in a Nordic Country. Educational Researcher. ISSN 0013-189X. 52(4). doi: 10.3102/0013189X221142596. Full text in Research Archive Show summary

  We study a decade of achievement gaps for fifth-, eighth-, and 10th-grade students in Norway using administrative population data. Norway is a wealthy and egalitarian country with a homogeneous educational system, yet achievement gaps between students at the 90th and 10th percentiles of parental income and between students whose parents have at least a master and at most a high school degree are found to be large (0.55–0.93 and 0.70–0.99 SD), equivalent to about 2 to 2.5 years of schooling, and increasing by grade level. Achievement gaps by parental income, but not by parental education, increased over the time period, underscoring the different ways these two socioeconomic status components relate to achievement and the potential for policy to alter gaps.

• Cheesman, Rosa Catherine Gillespie; Borgen, Nicolai T.; Lyngstad, Torkild Hovde; Eilertsen, Espen Moen; Ayorech, Ziada & Torvik, Fartein Ask [Show all 9 contributors for this article] (2022). A population-wide gene-environment interaction study on how genes, schools, and residential areas shape achievement. npj Science of learning. Full text in Research Archive
• Cheesman, Rosa Catherine Gillespie; Borgen, Nicolai Topstad; Lyngstad, Torkild Hovde; Eilertsen, Espen Moen; Ayorech, Ziada & Torvik, Fartein Ask [Show all 9 contributors for this article] (2022). A population-wide gene-environment interaction study on how genes, schools, and residential areas shape achievement. npj Science of learning. 7, p. 1–9. doi: 10.1038/s41539-022-00145-8. Full text in Research Archive Show summary

  Abstract A child’s environment is thought to be composed of different levels that interact with their individual genetic propensities. However, studies have not tested this theory comprehensively across multiple environmental levels. Here, we quantify the contributions of child, parent, school, neighbourhood, district, and municipality factors to achievement, and investigate interactions between polygenic indices for educational attainment (EA-PGI) and environmental levels. We link population-wide administrative data on children’s standardised test results, schools and residential identifiers to the Norwegian Mother, Father, and Child Cohort Study (MoBa), which includes >23,000 genotyped parent-child trios. We test for gene-environment interactions using multilevel models with interactions between EA-PGI and random effects for school and residential environments (thus remaining agnostic to specific features of environments). We use parent EA-PGI to control for gene-environment correlation. We found an interaction between students’ EA-PGI and schools suggesting compensation: higher-performing schools can raise overall achievement without leaving children with lower EA-PGI behind. Differences between schools matter more for students with lower EA-PGI, explaining 4 versus 2% of the variance in achievement for students 2 SD below versus 2 SD above the mean EA-PGI. Neighbourhood, district, and municipality variation contribute little to achievement (<2% of the variance collectively), and do not interact with children’s individual EA-PGI. Policy to reduce social inequality in achievement in Norway should focus on tackling unequal support across schools for children with difficulties.

• Lyhmann, Ingvild; Widding-Havnerås, Tarjei; Zachrisson, Henrik Daae; Bjelland, Ingvar; Chaulagain, Ashmita & Mykletun, Arnstein [Show all 7 contributors for this article] (2022). Variation in attitudes toward diagnosis and medication of ADHD: a survey among clinicians in the Norwegian child and adolescent mental health services. European Child and Adolescent Psychiatry. ISSN 1018-8827. doi: 10.1007/s00787-022-02110-7. Full text in Research Archive Show summary

  Prevalence and medication rates of ADHD vary geographically, both between and within countries. No absolute cutoff exists between ADHD and normal behavior, making clinician attitudes (leading to local practice cultures) a potential explanation for the observed variation in diagnosis and medication rates. The objective of this study was to describe variation in attitudes toward diagnosis and medication of ADHD among clinicians working in child and adolescent mental health services (CAMHS). We hypothesized that attitudes would vary along a spectrum from “restrictive” to “liberal”. We also explored whether differences in attitudes between clinicians were related to professional background and workplace (clinic). A survey in the form of a web-based questionnaire was developed. All CAMHS outpatient clinics in Norway were invited. Potential respondents were all clinicians involved in diagnosing and treating children and adolescents with ADHD. To investigate the existence of attitudes toward diagnosis and medication as latent constructs, we applied confirmatory factor analysis (CFA). We further examined how much of variance in attitudes could be ascribed to profession and clinics by estimating intraclass correlation coefficients. In total, 674 respondents representing 77 (88%) of the clinics participated. We confirmed variation in attitudes with average responses leaning toward the “restrictive” end of the spectrum. CFA supported “attitude toward diagnosis” and “attitude toward medication” as separate, and moderately correlated (r = 0.4) latent variables, representing a scale from restrictive to liberal. Professional background and workplace explained only a small part of variance in these attitudes.

• Isungset, Martin Arstad; Conley, Dalton C; Zachrisson, Henrik Daae; Ystrøm, Eivind; Havdahl, Alexandra & Njølstad, Pål Rasmus [Show all 7 contributors for this article] (2022). Social and genetic associations with educational performance in a Scandinavian welfare state. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 119(25). doi: 10.1073/pnas.2201869119. Full text in Research Archive Show summary

  Recent research has suggested that across Western developed societies, the influence of genetics on educational outcomes is relatively constant. However, the degree to which family environment matters varies, such that countries with high levels of intergenerational mobility have weaker associations of family background. Research in this vein has relied on twin-based estimates, which involve variance decomposition, so direct assessment of the association of genes and environments is not possible. In the present study, we approach the question by directly measuring the impact of child genotype, parental genetic nurture, and parental realized education on educational achievement in primary and secondary school. We deploy data from a social democratic context (Norway) and contrast our findings with those derived from more liberal welfare state contexts. Results point to genetics only confounding the relationship between parent status and offspring achievement to a small degree. Genetic nurture associations are similar to those in other societies. We find no, or very small, gene–environment interactions and parent–child genotype interactions with respect to test scores. In sum, in a Scandinavian welfare state context, both genetic and environmental associations are of similar magnitude as in societies with less-robust efforts to mitigate the influence of family background.

• Widding-Havneraas, Tarjei; Markussen, Simen; Elwert, Felix; Lyhmann, Ingvild; Bjelland, Ingvar & Halmøy, Anne [Show all 10 contributors for this article] (2022). Geographical variation in ADHD: do diagnoses reflect symptom levels? European Child and Adolescent Psychiatry. ISSN 1018-8827. 32. doi: 10.1007/s00787-022-01996-7. Full text in Research Archive Show summary

  Rates of ADHD diagnosis vary across regions in many countries. However, no prior study has investigated how much within-country geographic variation in ADHD diagnoses is explained by variation in ADHD symptom levels. We examine whether ADHD symptom levels explain variation in ADHD diagnoses among children and adolescents using nationwide survey and register data in Norway. Geographical variation in incidence of ADHD diagnosis was measured using Norwegian registry data from the child and adolescent mental health services for 2011–2016. Geographical variation in ADHD symptom levels in clinics’ catchment areas was measured using data from the Norwegian mother, father and child cohort study for 2011–2016 (n = 39,850). Cross-sectional associations between ADHD symptom levels and the incidence of ADHD diagnoses were assessed with fractional response models. Geographical variation in ADHD diagnosis rates is much larger than what can be explained by geographical variation in ADHD symptoms levels. Treatment in the Norwegian child and adolescent mental health services is free, universally available upon referral, and practically without competition from the private sector. Factors beyond health care access and unequal symptom levels seem responsible for the geographical variation in ADHD diagnosis.

• Widding-Havneraas, Tarjei & Zachrisson, Henrik Daae (2022). A gentle introduction to instrumental variables. Journal of Clinical Epidemiology. ISSN 0895-4356. 149, p. 1–3. doi: 10.1016/j.jclinepi.2022.06.022. Full text in Research Archive Show summary

  Instrumental variables (IV) is a central strategy for identifying causal effects in absence of randomized experiments. Clinicians and epidemiologists may find the intuition of IV easy to grasp by comparison to randomized experiments. Randomization is an ideal IV because treatment is assigned randomly, and hence unaffected by everything else. IV methods in nonexperimental settings mimic a randomized experiment by using a source of “as good as” random variation in treatment instead. The main challenge with IV designs is to find IVs that are as good as randomization. Discovering potential IVs require substantive knowledge and an understanding of design principles. Moreover, IV methods recover causal effects for a subset of the population who take treatment when induced by the IV. Sometimes these estimates are informative, other times their relevance is questionable. We provide an introduction to IV methods in clinical epidemiology. First, we introduce the main principles and assumptions. Second, we present practical examples based on Mendelian randomization and provider preference and refer to other common IVs in health. Third, practical steps in IV analysis are presented. Fourth, the promise and perils of IV methods are discussed. Finally, we suggest further readings.

• Cheesman, Rosa Catherine Gillespie; Eilertsen, Espen Moen; Ayorech, Ziada; Borgen, Nicolai Topstad; Andreassen, Ole & Larsson, Henrik [Show all 9 contributors for this article] (2022). How interactions between ADHD and schools affect educational achievement: a family-based genetically sensitive study. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. 63(10), p. 1174–1185. doi: 10.1111/jcpp.13656. Full text in Research Archive Show summary

  Background Children with ADHD tend to achieve less than their peers in school. It is unknown whether schools moderate this association. Nonrandom selection of children into schools related to variations in their ADHD risk poses a methodological problem. Methods We linked data on ADHD symptoms of inattention and hyperactivity and parent–child ADHD polygenic scores (PGS) from the Norwegian Mother, Father, and Child Cohort Study (MoBa) to achievement in standardised tests and school identifiers. We estimated interactions of schools with individual differences between students in inattention, hyperactivity, and ADHD-PGS using multilevel models with random slopes for ADHD effects on achievement over schools. In our PGS analyses, we adjust for parental selection of schools by adjusting for parental ADHD-PGS (a within-family PGS design). We then tested whether five school sociodemographic measures explained any interactions. Results Analysis of up to 23,598 students attending 2,579 schools revealed interactions between school and ADHD effects on achievement. The variability between schools in the effects of inattention, hyperactivity and within-family ADHD-PGS on achievement was 0.08, 0.07 and 0.05 SDs, respectively. For example, the average effect of inattention on achievement was β = −0.23 (SE = 0.009), but in 2.5% of schools with the weakest effects, the value was −0.07 or less. ADHD has a weaker effect on achievement in higher-performing schools. Schools make more of a difference to the achievements of students with higher levels of ADHD, explaining over four times as much variance in achievement for those with high versus average inattention symptoms. School sociodemographic measures could not explain the ADHD-by-school interactions. Conclusions Although ADHD symptoms and genetic risk tend to hinder achievement, schools where their effects are weaker do exist. Differences between schools in support for children with ADHD should be evened out.

• Ribeiro, Luisa Jacinta Feio Antunes; Zachrisson, Henrik Daae; Nærde, Ane; Wang, Mari Vaage; Brandlistuen, Ragnhild Eek & Passaretta, Giampiero (2022). Socioeconomic disparities in early language development in two Norwegian samples. Applied Developmental Science. ISSN 1088-8691. 27(2), p. 188–188. doi: 10.1080/10888691.2022.2051510. Full text in Research Archive Show summary

  Socioeconomic disparities in early language are widespread and have long-lasting effects. The aim of this study is to investigate when social gaps in language problems arise and how they change across the first years of schooling. We address this question in two large longitudinal Norwegian datasets: the Behavior Outlook Norwegian Developmental Study (BONDS) and the Norwegian Mother, Father and Child Cohort Study (MoBa). Despite some slight differences across the two samples, we found that children from higher social backgrounds are less likely to have language difficulties starting from age 18 months and up to age 8 (grade 2). Moreover, while early language problems are strongly predictive of later language, maternal education makes an additional contribution to explaining language difficulties at the beginning of school life. Social inequality in language development arises early, even in a country like Norway, with low unemployment and one of the most egalitarian societies in Europe.

• Rey-Guerra, Catalina; Zachrisson, Henrik Daae; Dearing, Eric Curtis; Berry, Daniel; Kuger, Susanne & Burchinal, Margaret R. [Show all 9 contributors for this article] (2022). Do more hours in center‐based care cause more externalizing problems? A cross‐national replication study. Child Development. ISSN 0009-3920. 94(2), p. 477–477. doi: 10.1111/cdev.13871. Full text in Research Archive Show summary

  Whether high quantities of center‐based care cause behavior problems is a controversial question. Studies using covariate adjustment for selection factors have detected relations between center care and behavior problems, but studies with stronger internal validity less often find such evidence. We examined whether within‐child changes in hours in center‐based care predicted changes in externalizing problems in toddlers and preschoolers ( N  = 10,105; 49% female; data collection 1993–2012) in seven studies, including from Germany, Netherlands, Norway, two from Canada and two from the U.S. Race/ethnicity data were only collected in the United States (57% and 80% White; 42% and 13% African‐American; 1.2% and 5% Latinx). Meta‐analyses showed no association ( r  = .00, p  = .88) between hours in center‐based care and externalizing problems.

• Bustamante, Andres S.; Dearing, Eric; Zachrisson, Henrik Daae & Vandell, Deborah Lowe (2021). Adult outcomes of sustained high-quality early child care and education: Do they vary by family income? Child Development. ISSN 0009-3920. doi: 10.1111/cdev.13696. Full text in Research Archive Show summary

  Experimental research demonstrates sustained high-quality early care and education (ECE) can mitigate the consequences of poverty into adulthood. However, the long-term effects of community-based ECE are less known. Using the 1991 NICHD Study of Early Child Care and Youth Development (n = 994; 49.7% female; 73.6% White, 10.6% African American, 5.6% Latino, 10.2% Other), results show that ECE was associated with reduced disparities between low- and higher-income children's educational attainment and wages at age 26. Disparities in college graduation were reduced the more months that low-income children spent in ECE (d = .19). For wages, disparities were reduced when children from low-income families attended sustained high-quality ECE (d = .19). Findings suggest that community-based ECE is linked to meaningful educational and life outcomes, and sustained high-quality ECE is particularly important for children from lower-income backgrounds.

• Mykletun, Arnstein; Widding-Havneraas, Tarjei; Chaulagain, Ashmita; Lyhmann, Ingvild; Bjelland, Ingvar & Halmøy, Anne [Show all 11 contributors for this article] (2021). Causal modelling of variation in clinical practice and long-term outcomes of ADHD using Norwegian registry data: The ADHD controversy project. BMJ Open. 11:e041698(1), p. 1–13. doi: 10.1136/bmjopen-2020-041698. Full text in Research Archive Show summary

  Introduction Attention-deficit/hyperactivity disorder (ADHD) is among the most common mental disorders in children and adolescents, and it is a strong risk factor for several adverse psychosocial outcomes over the lifespan. There are large between-country and within-country variations in diagnosis and medication rates. Due to ethical and practical considerations, a few studies have examined the effects of receiving a diagnosis, and there is a lack of research on effects of medication on long-term outcomes. Our project has four aims organised in four work packages: (WP1) To examine the prognosis of ADHD (with and without medication) compared with patients with other psychiatric diagnoses, patients in contact with public sector child and adolescent psychiatric outpatient clinics (without diagnosis) and the general population; (WP2) Examine within-country variation in ADHD diagnoses and medication rates by clinics’ catchment area; and(WP3) Identify causal effects of being diagnosed with ADHD and (WP4) ADHD medication on long-term outcomes. Method and analysis Our project links several nationwide Norwegian registries. The patient sample is all persons aged 5–18 years that were in contact with public sector child and adolescent psychiatric outpatient clinics in 2009–2011. Our comparative analysis of prognosis will be based on survival analysis and mixed-effects models. Our analysis of variation will apply mixed-effects models and generalised linear models. We have two identification strategies for the effect of being diagnosed with ADHD and of receiving medication on long-term outcomes. Both strategies rely on using preference-based instrumental variables, which in our project are based on provider preferences for ADHD diagnosis and medication. Ethics and dissemination The project is approved by the Regional Ethics Committee, Norway (REC number 2017/2150/REC south-east D). All papers will be published in open-access journals and results will be presented in national and international conferences. Trial registration numbers ISRCTN11573246 and ISRCTN11891971.

• Østbø, Ingvild Ulven & Zachrisson, Henrik Daae (2021). Student Motivation and Parental Attitude as Mediators for SES Effects on Mathematics Achievement: Evidence from Norway in TIMSS 2015. Scandinavian Journal of Educational Research. ISSN 0031-3831. p. 1–16. doi: 10.1080/00313831.2021.1939138. Full text in Research Archive Show summary

  Using data collected from 4329 students in the 2015 iteration of the Trends in Mathematics and Science Study (TIMSS), we explore two mediators for the relationship between socioeconomic status (SES) and TIMSS-results in mathematics among Norwegian fifth graders. First, we explore how the students’ motivation and self-concept mediate the relationship between SES and test results. Second, by using parent reported SES resources and the parents’ attitudes to school and the tested subjects, we examine how these may constitute a path through which their children’s motivation and family SES are related to mathematics achievement. We found that students’ self-concept accounted for a small but statistically significant portion of SES effects on achievement. Intrinsic motivation did not mediate any of the SES effects on achievement, nor did parental attitudes account for any of the association between SES and motivation or achievement.

• Widding-Havneraas, Tarjei; Chaulagain, Ashmita; Lyhmann, Ingvild; Zachrisson, Henrik Daae; Elwert, Felix & Markussen, Simen [Show all 8 contributors for this article] (2021). Preference-based instrumental variables in health research rely on important and underreported assumptions: a systematic review. Journal of Clinical Epidemiology. ISSN 0895-4356. 139, p. 268–278. doi: 10.1016/j.jclinepi.2021.06.006. Full text in Research Archive Show summary

  Objective: Preference-based instrumental variables (PP IV) designs can identify causal effects when patients receive treatment due to variation in providers’ treatment preference. We offer a systematic review and methodological assessment of PP IV applications in health research. Study Design and Setting: We included studies that applied PP IV for evaluation of any treatment in any population in health research (PROSPERO: CRD42020165014). We searched within four databases (Medline, Web of Science, ScienceDirect, SpringerLink) and four journals (including full-text and title and abstract sources) between January 1, 1998, and March 5, 2020. We extracted data on areas of applications and methodology, including assumptions using Swanson and Hernan's (2013) guideline. Results: We included 185 of 1087 identified studies. The use of PP IV has increased, being predominantly used for treatment effects in cancer, cardiovascular disease, and mental health. The most common PP IV was treatment variation at the facility-level, followed by physician- and regional-level. Only 12 percent of applications report the four main assumptions for PP IV. Selection on treatment may be a potential issue in 46 percent of studies. Conclusion: The assumptions of PP IV are not sufficiently reported in existing work. PP IV-studies should use reporting guidelines.

• Alexandersen, Nina; Zachrisson, Henrik Daae; Wilhelmsen, Tiril; Wang, Mari Vaage & Brandlistuen, Ragnhild Eek (2021). Predicting selection into ECEC of higher quality in a universal context:The role of parental education and income. Early Childhood Research Quarterly. ISSN 0885-2006. 55, p. 336–348. doi: 10.1016/j.ecresq.2021.01.001. Full text in Research Archive Show summary

  There is consensus about the positive effects of high quality Early Childhood Education and Care (ECEC) on children’s development, particularly for children from lower socioeconomic backgrounds. However, limited knowledge exists on the access to quality in ECEC in a universal context. This study investigates potential socioeconomic selection into ECEC of higher structural quality in the context of a universal, heavily subsidized, and regulated system in Norway, intended to provide equal access to high quality ECEC. Furthermore, we explore the impact of SES and structural quality in ECEC on student-teacher relationship quality. Our conceptual model takes into account how readily accessible information on different quality aspects is for parents. We use data from the Norwegian Mother, Father and Child Cohort Study linked with teacher-reported ECEC quality for children born in 2006–2009 (N 7,226), supplemented by registry data at ECEC and municipality level. We find that higher parental education, and to a lesser degree income, predict child attendance of ECEC with higher structural quality as rated by ECEC teachers. Further, higher parental SES and structural quality (i.e., developmental material, staff competence and stability) predict better student-teacher relationship quality in terms of higher level of closeness and less conflict. These findings suggest that ambitions of universal equal access to high quality ECEC are not entirely realized and more efforts are needed to ensure higher structural quality in ECEC and enhance relationship quality for children from less advantageous socioeconomic backgrounds.

• Torvik, Fartein Ask; Eilertsen, Espen Moen; McAdams, Tom A.; Gustavson, Kristin; Zachrisson, Henrik Daae & Brandlistuen, Ragnhild Eek [Show all 11 contributors for this article] (2020). Mechanisms linking parental educational attainment with child ADHD, depression, and academic problems: a study of extended families in The Norwegian Mother, Father and Child Cohort Study. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. 61(9), p. 1009–1018. doi: 10.1111/jcpp.13197. Full text in Research Archive Show summary

  Background: Low educational attainment in parents is associated with child psychopathology. It is not clear whether the associations are due to risk factors that family members share or due to effects of maternal or paternal education on the offspring. We investigate whether associations between maternal and paternal educational attainment and child symptoms of attention deficit/hyperactivity disorder (ADHD), depression, and academic problems are due to shared genetic factors, shared family environmental factors, or effects of the parental phenotype educational attainment itself. Methods: This study is based on the Norwegian Mother, Father and Child Cohort Study (MoBa). The sample comprised 34,958 children (17,128 girls) in 28,372 extended‐family units. We used data from related nuclear families linked by siblings in the parent generation. We applied a quasi‐experimental extended children‐of‐twins design that included siblings in both generations and took account of nonrandom mating by including partners. Educational attainment was self‐reported by mothers and fathers. Mothers reported children's symptoms of ADHD, symptoms of depression, and academic problems by questionnaire when the children were 8 years old. Results: Children of lowly educated parents scored higher on all outcomes and had an approximate doubling of the risk of high symptom levels. The association between maternal and paternal educational attainment and child symptoms of ADHD and academic problems persisted after controlling for shared genetic and family environmental factors. Phenotypic transmission to depression was weaker and in the best fitting model fully explained by genetic factors shared by the two generations. Conclusions: Associations between educational attainment of mothers and fathers and child symptoms of ADHD and academic problems could not be ascribed to shared familial risk factors, whereas associations with symptoms of depression could. Parental education or resources and behaviors resulting from low education might be targets of interventions aimed at reducing symptoms of ADHD and academic problems.

• Ribeiro, Luisa Jacinta Feio Antunes; Casey, Beth; Dearing, Eric Curtis; Nordahl, Kristin Berg; Aguiar, Cecilia & Zachrisson, Henrik Daae (2020). Early Maternal Spatial Support for Toddlers and Math Skills in Second Grade. Journal of Cognition and Development. ISSN 1524-8372. 21(2), p. 282–311. doi: 10.1080/15248372.2020.1717494. Full text in Research Archive Show summary

  The aim of this study is to investigate whether maternal spatial support during two types of joint manipulative toy play tasks with 2-year-old children was longitudinally associated with math screening test scores in second grade. The interaction between spatial support and maternal education was explored as well. We also investigated predictions of a teacher rating of math performance at second grade, although these effects were less robust. Data were drawn from BONDS (The Behavior Outlook Norwegian Developmental Study), a longitudinal study of Norwegian children and their families. Participants were a subsample of 932 mothers and their 2-year-olds. Mothers were asked to help their children solve both a puzzle task and a shape-color sorting task. Mothers’ spatial support included spatial language, gestures, and placement of objects. Results showed that higher levels of spatial support during mother-child interaction tasks at 2 years of age was significantly associated with fewer math difficulties in second grade. This was the case for a puzzle task (a task associated with spatial visualization skills), but not for a shape-color sorting task (a task associated with shape and color feature discriminations). Conclusions are drawn with respect to the importance of identifying optimal parental spatial strategies associated with better math outcomes. These findings on parental facilitation of spatial skills during joint early play may be useful for future training interventions directed at parents of children at risk for poor math skills.

• Nordahl, Kristin Berg; Owen, Margaret Tresch; Ribeiro, Luisa Jacinta Feio Antunes & Zachrisson, Henrik Daae (2020). Parenting quality from observational ratings at age 2: validation from Norwegian and U.S. Samples. Early Childhood Research Quarterly. ISSN 0885-2006. 53(4), p. 379–390. doi: 10.1016/j.ecresq.2020.05.010. Full text in Research Archive Show summary

  This study investigated the construct validity of a proposed measure of parenting quality derived from extensively used observational ratings of parenting in mother-child interaction procedures with 2-year-olds in two large samples. Data included global ratings of mother-child interaction in an unstructured free-play and a semi-structured teaching task from the Behavior Outlook Norwegian Developmental Study (N = 1157) and from the Three Boxes procedure used in the NICHD Study of Early Child Care and Youth Development (N = 1364). Confirmatory Factor Analyses, including ratings of mothers’ sensitivity, detachment, intrusiveness, cognitive stimulation, positive regard and negative regard, revealed a similarly structured latent parenting construct across samples and observational procedures, supporting the structural and content validity, and the generalizability of the measure. In the Norwegian sample, better predictive validity to child outcomes at age 4 was found from the semi-structured teaching task than from the less structured free-play task. Comparable predictive validity to child outcomes was found for the U.S. sample’s latent parenting quality construct. The results hold implications for the careful selection and study of observational procedures for measuring parenting quality in early childhood.

• Zachrisson, Henrik Daae; Owen, Margaret T.; Nordahl, Kristin Berg; Ribeiro, Luisa & Dearing, Eric Curtis (2020). Too Early for Early Education? Effects on Parenting for Mothers and Fathers. Journal of Marriage and Family. ISSN 0022-2445. doi: 10.1111/jomf.12701. Full text in Research Archive Show summary

  Objective To estimate the effect of children's age of entry into early childhood education and care (ECEC) on parenting quality of mothers and fathers in a context of universal access to subsidized ECEC following a 1 year paid parental leave. Background Children entering non‐parental care settings in early childhood may have negative consequences for parenting quality. Yet, current evidence supporting this claim is predominantly from the United States, is focused almost exclusively on mothers, and is predominantly based on statistical approaches that are vulnerable to unobserved selection bias. Method Data are from a Norwegian longitudinal study, including ratings of observed mother–child (n = 901) and father–child (n = 621) interactions, and children's age of entry into ECEC. Multivariate regression models and instrumental variable models were used to estimate the causal effect of age of entry on parenting quality. Results There was no support for the hypothesis that an earlier age of entry into ECEC negatively affects parenting quality, for either fathers or mothers. This was true for the sample as a whole, and for different sociodemographic subgroups. Conclusion In a Norwegian context in which families have universal access to subsidized ECEC from the time their child is 1 year of age, and most children enter ECEC in their second year, there is no evidence that an earlier age of entry in ECEC harms parenting quality.

• Strietholt, Rolf; Hogrebe, Nina & Zachrisson, Henrik Daae (2020). Do increases in national-level preschool enrollment increase student achievement? Evidence from international assessments. International Journal of Educational Development. ISSN 0738-0593. doi: 10.1016/j.ijedudev.2020.102287. Full text in Research Archive Show summary

  The main purpose of the study is to analyze whether globally observed trends towards preschool expansion have impacted student achievement in primary and secondary school. We use data from multiple study cycles of two international large-scale assessments that have a longitudinal component at the country level—PIRLS and PISA—and combine these data with a country-level measure of preschool enrollment rates as the main explanatory variable. Employing a multilevel regression with fixed effects for countries and years, we find that changes in preschool enrollment are unrelated to changes in average student achievement. Even after controlling for covariates on the individual and country levels, we do not find any support for the policy expectation that expanding preschool enrollment per se leads to better student achievement on country level.

• Zambrana, Imac Maria; Ogden, Terje & Zachrisson, Henrik Daae (2019). Can Pre-Academic Activities in Norway’s Early Childhood Education and Care Program Boost Later Academic Achievements in Preschoolers at Risk? Scandinavian Journal of Educational Research. ISSN 0031-3831. doi: 10.1080/00313831.2019.1577751. Full text in Research Archive Show summary

  Low academic achievements are predicted by early disadvantages. Because achievement gaps typically escalate with age, early efforts to prevent future academic disadvantages are called for. The current study examines whether exposure to structured pre-academic activities in Early Childhood Education and Care (ECEC) play a compensatory role for the early academic achievements in school (teacher ratings and screening tests of reading and math) of children who were at developmental (low receptive language), behavioral (high externalizing behavior and low effortful control) and socio-economic (low maternal education) risk in preschool. Using a sample of 934 children from the longitudinal Behavioral Outlook Developmental Study to examine between-school comparisons and within-school fixed effects models, findings suggest that preschoolers with externalizing behaviors may moderately benefit from structured pre-academic activities prior to school entry. However, it is concluded that this pre-academic boost is weak and may be limited to a short transition period from ECEC to school.

• Dearing, Eric Curtis & Zachrisson, Henrik Daae (2019). Taking Selection Seriously in Correlational Studies of Child Development: A Call for Sensitivity Analyses. Child Development Perspectives (CDP). ISSN 1750-8592. doi: 10.1111/cdep.12343. Full text in Research Archive Show summary

  Correlational studies have played a major role in building our cumulative knowledge on child development. Yet as a result, we often have difficulty making causal inferences. The concern is selection effects: When children have not been randomly assigned to conditions, pre-existing biological, psycho- logical, or social factors may bias correlations. In this article, we draw attention to sensitivity analyses, statis- tical techniques for estimating the robustness or fragility of results in light of potential selection effects. We high- light the coefficient of proportionality method recently developed by Oster (2019), which does not require assumptions about the number of omitted selection vari- ables. The coefficient of proportionality provides an indication of how large the impact of unobserved selec- tion factors would need to be—relative to observed covariates—to nullify a result. We offer two empirical examples to demonstrate the value of this method com- pared with other approaches used by child development researchers.

• Feyer, Frida Karine & Zachrisson, Henrik Daae (2019). Country Reports: Norway. In Guerra, Joana; Leitão, Catarina & Barata, Clara (Ed.), Interview study of service providers and coordinators on interagency coordination for children and families. Policies and practices in nine European countries. ISOTIS D6.3 Report. Inclusive Education and Social Support to Tackle Inequalities in Society. p. 100–112. Full text in Research Archive Show summary

  Interview study of service providers and coordinators on interagency coordination for children and families. Policies and practices in nine European countries. The collaboration between services for children and families has the potential of tackling inequalities

• Ribeiro, Luisa Jacinta Feio Antunes & Zachrisson, Henrik Daae (2019). Peer Effects on Aggressive Behavior in Norwegian Child Care Centers. Child Development. ISSN 0009-3920. 90(3), p. 876–893. doi: 10.1111/cdev.12953. Full text in Research Archive Show summary

  This study examined whether exposure to changes in peer aggression predicted changes in child physical aggression (PA) in preschool children attending Norwegian Early Childhood Education and Care (ECEC) centers. Data from the Behavior Outlook Norwegian Developmental Study were used, including 956 children. In fixed effects models, within‐child changes in exposure to peer aggression predicted changes in teacher‐rated child PA across ages 2, 3, and 4. Moreover, changes in exposure to a peer group with two or more externalizing children increased teacher‐rated child PA over time, but only for boys. No significant peer effects on parent‐rated child PA were found. Findings point to the importance of avoiding the congregation of several problematic children, particularly boys, in the same ECEC groups.

• Zachrisson, Henrik Daae; Janson, Harald & Lamer, Kari (2019). The Lamer Social Competence in Preschool (LSCIP) Scale: Structural Validity in a Large Norwegian Community Sample. Scandinavian Journal of Educational Research. ISSN 0031-3831. 63(4), p. 551–565. doi: 10.1080/00313831.2017.1415963. Full text in Research Archive Show summary

  There is an increasing emphasis on the importance of social competence for children’s development, well-being, and learning. Thus age- and context-appropriate measures are needed. This study addresses the structural validity of the Lamer Social Competence in Preschool (LSCIP) scale, developed to accommodate the Nordic model of early childhood pedagogy. The authors specify the theoretical basis for a bi-factor model of social competence. This model is tested in a large (n=1157), community based sample of Norwegian children, including teacher- (at age 2, 3, and 4), mother- (at age 4), and father- (at age 3) reports. A model with a main factor for social competence, and three bi-factors fit data across ages and reporters, with factorial, but not strong, invariance over time.

• Kjøbli, John; Zachrisson, Henrik Daae & Bjørnebekk, Gunnar (2018). Three Randomized Effectiveness Trials — One Question: Can Callous-Unemotional Traits in Children Be Altered? Journal of Clinical Child & Adolescent Psychology. ISSN 1537-4416. 47(3), p. 436–443. doi: 10.1080/15374416.2016.1178123. Full text in Research Archive Show summary

  Children with conduct problems and callous-unemotional (CU) traits are at risk for multiple problems. Outcome research and mediation analyses testing for mechanisms of change in CU traits have been limited. We examined whether parent training—in a short-term (Brief Parent Training; BPT) or a comprehensive format (Parent Management Training, Oregon Model; PMTO)—or child-directed social skills training (Individual Social Skills Training [ISST]) produced positive effects on CU traits. In mediation models we tested parenting practices as mechanisms of change for CU traits. We pooled data from three randomized effectiveness trials, and 551 families were included in this study. Families had children between 3 and 12 years of age and displayed emerging or present conduct problems at home, day care, or school (BPT M age = 7.28, 31.9% girls; PMTO M age = 8.56, 36.5% girls; ISST M age = 7.64, 19.7% girls). Assessments were completed preintervention, postintervention, and at follow-up (6 months following intervention). Both BPT (d = .32) and PMTO (d = .39) had positive effects on CU traits at posttest, whereas ISST did not (d = –.06). At follow-up, only PMTO produced a significant effect (d = .48) on CU traits. A significant indirect effect on CU traits emerged by positive parenting. Both parent training conditions outperformed ISST. Only PMTO maintained its effects at follow-up. The findings suggest that PMTO can reduce CU traits and that improved positive parenting is associated with positive outcomes for children’s CU traits.

• Eliassen, Erik; Zachrisson, Henrik Daae & Melhuish, Edward (2018). Is cognitive development at three years of age associated with ECEC quality in Norway? European Early Childhood Education Research Journal. ISSN 1350-293X. 26(1), p. 97–110. doi: 10.1080/1350293X.2018.1412050. Full text in Research Archive Show summary

  In countries with universal access to early childhood education and care (ECEC), child participation is high across a range of socioeconomic groups. However, ECEC quality is often varying, and many children spend much time in ECEC settings that are not necessarily high quality. In this observational study, we therefore examined the relationship between observed ECEC quality and children’s cognitive development at age three years in Norway–a country that provides universal access to ECEC from age one. The sample comprised 800 children, enrolled in 83 ECEC centers, who were assessed in verbal and non-verbal cognitive ability. ECEC quality was measured with the Infant/Toddler Environment Rating Scale (ITERS-R), and cognitive outcomes were measured with the Naming Vocabulary and Picture Similarities subtests of the British Ability Scales III (BAS III). The results showed that children’s cognitive development at age three was not associated with ECEC quality; irrespective of socioeconomic background.

• Dearing, Eric; Zachrisson, Henrik Daae; Mykletun, Arnstein & Toppelberg, Claudio O (2018). Estimating the Consequences of Norway’s National Scale-Up of Early Childhood Education and Care (Beginning in Infancy) for Early Language Skills. AERA Open. 4(1), p. 1–16. doi: 10.1177/2332858418756598. Full text in Research Archive Show summary

  While most early childhood education and care (ECEC) programs taken to scale in the United States have served socially disadvantaged 3- to 5-years-olds, Norway scaled up universal ECEC from age 1. We investigated the consequences of Norway’s universal ECEC scale-up for children’s early language skills, exploiting variation in ECEC coverage across birth cohorts and municipalities in a population-based sample (n = 63,350). Estimates from two-stage least squares (i.e., instrumental variable) regression and generalized difference-in-differences models indicated the scale-up of universal ECEC led to improved language outcomes, particularly for low-income children. As preschool programs at scale become increasingly common in the United States, our results from Norway help inform debate about the merits of universal versus targeted policies and should provoke discussion about the benefits of beginning ECEC programs as early as infancy.

• Cook, Kyle DeMeo; Dearing, Eric & Zachrisson, Henrik Daae (2018). Is Parent-Teacher Cooperation in the First Year of School Associated with Children's Academic Skills and Behavioral Functioning? International Journal of Early Childhood. ISSN 0020-7187. 50(2), p. 211–226. doi: 10.1007/s13158-018-0222-z. Full text in Research Archive Show summary

  The importance of parent engagement in children’s schooling is well documented, yet there is limited research on the quality of parent–teacher relationships specifically. In the present study, we aimed to help build knowledge in this area by investigating parent and teacher reports of home–school cooperation during children’s first year of school in Norway. Associations between parents’ and teachers’ reports of cooperation were examined as predictors of children’s academic skills and social functioning during their first year of school in Norway (N = 932). Controlling for children’s achievement and behavior prior to school entry, children whose parents and teachers both reported very good cooperation with one another were rated as having better academic skills and social skills and as having fewer negative behaviors than children whose parents and teachers did not report very good cooperation. In addition, if both parents and teachers reported very good cooperation, children’s academic skills were rated as higher than if parents and teachers disagreed such that one reported very good cooperation, but the other did not.

• Bøe, Tormod; Dearing, Eric; Stormark, Kjell Morten & Zachrisson, Henrik Daae (2017). Subjective economic status in adolescence: determinants and associations with mental health in the Norwegian Youth@ Hordaland Study. Journal of Family and Economic Issues. ISSN 1058-0476. Published ahead of print, p. 1–14. doi: 10.1007/s10834-017-9553-4. Full text in Research Archive Show summary

  We aimed to identify factors associated with perceived economic well-being (PEWB), and examine its association with symptoms of depression and attention-deficit/hyperactivity disorder. In the Norwegian youth@hordaland study, 9166 16–19-year-olds provided information on perceived economic well-being and relevant covariates. Information about families’ income-to-needs was obtained from tax return forms. Adolescents in households with a low income-to-needs ratio, with non-working parents, and in single-parent households were more likely to report poor PEWB. Adolescents with poor PEWB reported more symptoms of depression and ADHD, also after adjusting for covariates, including income-to-needs. There was a significant indirect effect of income-to-needs on mental health problems though PEWB. The current study demonstrates the role of PEWB as a contributor in the pathway from social inequalities to disparities in mental health.

• Lund, Terese J.; Dearing, Eric & Zachrisson, Henrik Daae (2017). Is affluence a risk for adolescents in Norway? Journal of Research on Adolescence. ISSN 1050-8392. 27(3), p. 628–643. doi: 10.1111/jora.12304. Full text in Research Archive Show summary

  Studies suggest that affluence poses a risk for adolescents, but this has rarely been studied outside the United States. We examined the unique and additive roles of family and school affluence for adolescent outcomes among 10th‐grade students (n = 7,203) in Oslo, Norway. Multilevel models were estimated separately by gender. For both boys and girls, school affluence was a risk for alcohol abuse and family affluence was a risk for conduct problems, although for conduct the risk was only at the very highest end of income distribution and adolescents in very poor families were also at risk. There was also a complex pattern of risk for early sexual debut; family affluence posed risk, but school affluence appeared protective. © 2017 Wiley

• Feyer, Frida Karine & Zachrisson, Henrik Daae (2017). Country profile: Norway. In Cadima, Joana; Nata, Gil; Evangelou, Maria & Anders, Yvonne (Ed.), Inventory and Analysis of Promising and Evidence-based Parent- and Family Focused Support Programs. ISOTIS report D3.2. Inclusive Education and Social Support to Tackle Inequalities in Society. p. 64–71. Full text in Research Archive Show summary

  This inventory focuses on promising and evidence-based parent- and family focused support services and programmes in ten European countries (Czech Republic, England, Germany, Netherlands, Norway, Poland and Portugal). The inventory starts by describing the social context indicators on family support and educational inequalities in each country. Second, the inventory presents country profiles, describing child and family services, and how country policies deal with equality issues, monitoring of services, and language support. Third, the inventory presents an analysis of a selected group of evidence-based and promising family support services and programmes, highlighting existing challenges and the programmes’ potential to overcome them. Finally, the inventory concludes with recommendations for potentially effective interventions in services and programmes design, implementation and evaluation. Ensuring outreach and adapting programmes to the country-specific contextual needs were some of the key recommendations highlighted by the authors. Comprehensive high-quality formative and summative evaluation studies of programmes are needed, particularly in those countries with underdeveloped research in this area.

• Petitclerc, Amelie; Côtè, Sylvana; Doyle, Orla; Burchinal, Margaret; Herba, Catherine & Zachrisson, Henrik Daae [Show all 11 contributors for this article] (2017). Who uses early childhood education and care services? Comparing socioeconomic selection across five western policy contexts. International Journal of Child Care and Education Policy. ISSN 1976-5681. 11(3). doi: 10.1186/s40723-017-0028-8. Full text in Research Archive
• Gjerde, Line C.; Eilertsen, Espen Moen; Reichborn-Kjennerud, Ted; McAdams, Tom A.; Zachrisson, Henrik Daae & Zambrana, Imac Maria [Show all 9 contributors for this article] (2017). Maternal perinatal and concurrent depressive symptoms and child behavior problems: a sibling comparison study. Journal of Child Psychology and Psychiatry. ISSN 0021-9630. 58(7), p. 779–786. doi: 10.1111/jcpp.12704. Full text in Research Archive Show summary

  Background: Previous studies have found significant associations between maternal prenatal and postpartum depression and child behavior problems (CBP). The present study investigates whether associations remain in a prospective, longitudinal design adjusted for familial confounding. Methods: The sample comprised 11,599 families including 17,830 siblings from the Norwegian Mother and Child Cohort study. Mothers reported depressive symptoms at gestational weeks 17 and 30, as well as 6 months, 1.5, 3, and 5 years postpartum. Fathers’ depression was measured at gestational week 17. At the last three time-points, child internalizing and externalizing problems were concurrently assessed. We performed multilevel analyses for internalizing and externalizing problems separately, using parental depression as predictors. Analyses were repeated using a sibling comparison design to adjust for familial confounding. Results: All parental depressive time-points were significantly and positively associated with child internalizing and externalizing problems. After sibling comparison, however, only concurrent maternal depression was significantly associated with internalizing [estimate = 2.82 (1.91–3.73, 95% CI)] and externalizing problems [estimate = 2.40 (1.56–3.23, 95% CI)]. The effect of concurrent maternal depression on internalizing problems increased with child age. Conclusions: Our findings do not support the notion that perinatal maternal depression is particularly detrimental to children's psychological development, as the most robust effects were found for maternal depression occurring during preschool years.

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• Peng, Qiyuan; Rietveld, Cornelius A.; Ystrom, Eivind; Zachrisson, Henrik Daae; Havdahl, Alexandra & Cheesman, Rosa Catherine Gillespie (2026). Does Universal Childcare Affect Early Child Development? Full text in Research Archive
• Bøe, Tormod & Zachrisson, Henrik Daae (2025). Hva betyr det for et barn å vokse opp i en fattig familie? Full text in Research Archive
• Bjermeland, Monica & Zachrisson, Henrik Daae (2025). Dette gjør at barn som vokser opp i familier med lav inntekt, kan få like gode muligheter som andre senere i livet. Forskning.no. ISSN 1891-635X. doi: https:/www.forskning.no/barn-og-ungdom-partner-psykologi/dette-gjor-at-barn-som-vokser-opp-i-familier-med-lav-inntekt-kan-fa-like-gode-muligheter-som-andre-senere-i-livet/2584949. Full text in Research Archive Show summary

  Muligheter til gode livserfaringer avgjør om barn fra de fattigste familiene lykkes senere i livet.

• Cheesman, Rosa Catherine Gillespie; Zachrisson, Henrik Daae & Bailey, Drew (2025). Gene-environment interplay and childcare decisions. Full text in Research Archive
• Zachrisson, Henrik Daae (2025). Quality at scale? A decade of large-scale evaluations of ECEC effects on child outcomes in Norway. Full text in Research Archive
• Zachrisson, Henrik Daae (2025). Seminar on Social Inclusion and Diversity in Nordic ECEC - Theory and practice - OKM - Ministry of Education and Culture, Finland. Full text in Research Archive Show summary

  Social Inclusion and Diversity in Nordic ECEC – research and practice

• Crawford, Duncan; Jones, Sephanie & Zachrisson, Henrik Daae (2025). How to ensure quality early childhood education and care for all - Top Class: The OECD Education Policy Podcast | Teachers, PISA, Students | Podcast on Spotify. Full text in Research Archive Show summary

  Top Class: The OECD Education Policy Podcast | Teachers, PISA, Students · Episode

• Hatlevik, Ove Edvard; Bjørnestad, Elisabeth; Zachrisson, Henrik Daae; Elnes, Magdalena & Melhuish, Edward Charles (2025). ECEC Quality and School Value Added: Additive and Interactive Associations to Academic Outcomes. Full text in Research Archive
• Widding-Havnerås, Tarjei; Demange, Perline Aline Delle; Elwert, Felix; Borgen, Nicolai T.; Ystrom, Eivind & Zachrisson, Henrik Daae (2024). Estimating Returns to Education Using Genetically Informed Designs. Full text in Research Archive
• Widding-Havnerås, Tarjei; Demange, Perline Aline Delle; Elwert, Felix; Borgen, Nicolai T.; Ystrom, Eivind & Zachrisson, Henrik Daae (2024). Estimating Returns to Education Using Genetically Informed Designs. Full text in Research Archive
• Widding-Havnerås, Tarjei; Demange, Perline Aline Delle; Elwert, Felix; Borgen, Nicolai T.; Ystrøm, Eivind & Zachrisson, Henrik Daae (2024). Estimating Returns to Education Using Genetically Informed Designs. Full text in Research Archive
• Borgen, Solveig Topstad; Borgen, Nicolai T. & Zachrisson, Henrik Daae (2023). Ethnic minorities in disadvantaged neighborhoods: Differential effects on educational outcomes. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Drange, Nina; Rege, Mari; Bøe, Tormod; Zachrisson, Henrik Daae; Salvanes, Kjell Gunnar & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Drange, Nina; Rege, Mari; Glemmestad, Hanne Solfrid; Salvanes, Kjell Gunnar; Fløtten, Tone & Bøe, Tormod [Show all 8 contributors for this article] (2023). En barndom for livet. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Haag, Katharina; Wang, Mari Vaage; Ask, Helga; Alexandersen, Nina; Zachrisson, Henrik Daae & Watts, Tyler [Show all 7 contributors for this article] (2023). Does Kindergarten quality moderate the effects of early risk on later childhood behavioural and academic outcomes? Full text in Research Archive
• Haag, Katharina; Wang, Mari Vaage; Ask, Helga; Alexandersen, Nina; Zachrisson, Henrik Daae & Watts, Tyler [Show all 7 contributors for this article] (2023). Can Kindergarten experiences moderate effects of early risk classes on middle childhood behavioural and academic outcomes?, Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). Dyrt og urealistisk å bekjempe fattigdom med økt barnetrygd – uten å skattlegge den. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). Barnetrygden bør økes – og skattlegges. Full text in Research Archive
• Drange, Nina Eirin; Rege, Mari; Bøe, Tormod; Zachrisson, Henrik Daae; Salvanes, Kjell Gunnar & Glemmestad, Hanne Solfrid [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Rege, Mari; Drange, Nina Eirin; Salvanes, Kjell Gunnar; Bøe, Tormod; Zachrisson, Henrik Daae & Glemmestad, Hanne Solfrid [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Full text in Research Archive
• Drange, Nina & Zachrisson, Henrik Daae (2022). På villspor om barnehagestart og psykiske lidelser. Full text in Research Archive
• Borgen, Solveig Topstad; Borgen, Nicolai T. & Zachrisson, Henrik Daae (2022). Ethnic minorities in disadvantaged neighborhoods: Differential effects on educational outcomes. Full text in Research Archive
• Wandem, Fredrik Solli; Zachrisson, Henrik Daae & Tisløv, Ingvild Stjernen (2022). Podkast: Fattigdom, ulikhet og barns utvikling. [Internet]. Universitetet i Oslo. Full text in Research Archive Show summary

  Episode i SpedAims-podkasten "Det virker!" Tusenvis av barn i Norge vokser opp i familier som lever i fattigdom. Hva betyr dette for barnas utvikling? Og hva kan vi gjøre for å hjelpe disse familiene?

• Badini, Isabella; Lyngstad, Torkild Hovde; Eilertsen, Espen Moen; Ahmadzadeh, Yasmin I.; Wechsler, Daniel L & Zachrisson, Henrik Daae [Show all 10 contributors for this article] (2021). Socioeconomic status and risk for child emotional and behavioral problems: Exploring gene-environment interaction in the presence of gene-environment correlation using extended families in the Norwegian Mother, Father and Child Birth Cohort Study. Full text in Research Archive
• Vartun, Marika & Zachrisson, Henrik Daae (2021). Hvordan bistå en forsker til å kommunisere forskning? Marika Vartun og Henrik Zachrisson, Universitetet i Oslo. Forskning får verdi gjennom kommunikasjon, og kommunikasjon er et evalueringskriterium i de fleste søknadstyper. Det forventes at forskere, i tillegg til de tradisjonelle fagfellekanalene, benytter ulike plattformer for å formidle forskningen sin ut i samfunnet. Vi får et eksempel på fruktbart samarbeid mellom forsker og kommunikasjonsrådgiver. Full text in Research Archive
• Badini, Isabella; Lyngstad, Torkild Hovde; Eilertsen, Espen Moen; Ahmadzadeh, Yasmin I.; Wechsler, Daniel L & Zachrisson, Henrik Daae [Show all 10 contributors for this article] (2021). Socioeconomic status and risk for child emotional and behavioral problems: Exploring gene-environment interaction in the presence of gene-environment correlation using extended families in the Norwegian Mother, Father and Child Birth Cohort Study. Behavior Genetics. ISSN 0001-8244. 51(6), p. 691–691. Full text in Research Archive
• Zachrisson, Henrik Daae; Vartun, Marika & Borge, Laila (2021). Kommunikasjonsarbeid gjør journalistene mindre skumle. [Internet]. NARMA Norsk nettverk for forskningsadministrasjon. Full text in Research Archive
• Alexandersen, Nina; Wilhelmsen, Tiril; Wang, Mari Vaage; Zachrisson, Henrik Daae & Brandlistuen, Ragnhild Eek (2019). Access to childcare quality in a universal context: the role of parental education and income. Full text in Research Archive
• Moser, Thomas & Zachrisson, Henrik Daae (2019). Universal ECEC as a protective mean for children from disadvantaged families in Norway? Full text in Research Archive
• Zachrisson, Henrik Daae & Ogden, Terje (2018). Tull eller tiltak? Om å tolke effektstørrelser i kontrollerte evalueringsstudier. Kontekstonline. ISSN 2535-4825. 1. doi: https:/www.nubu.no/no/forskning/tull-eller-tiltak. Full text in Research Archive Show summary

  Forskere snakker ofte om «signifikante resultater» når de mener å ha unnet ‘virkelige’ forskjeller, for eksempel mellom en ny behandlingsmetode og vanlig praksis. Men det er viktig også å bruke holdepunkter utenfor statistikken. Sunn fornuft, kritisk sans og vurdering av praktiske implikasjoner er vesentlig i en vurdering av om et tiltak har effekt. Artikkelen sto på trykk i den første utgaven av NUBUs digitale tidsskrift KONTEKSTonline som ble utgitt i februar 2018.

• Zambrana, Imac Maria; Ogden, Terje & Zachrisson, Henrik Daae (2017). Can pre-academic activities in ECEC boost later academic achievements in preschoolers with externalizing behaviors? Full text in Research Archive
• Eliassen, Erik & Zachrisson, Henrik Daae (2017). The causal effect of entry age on children's social competence at age 3 years. Full text in Research Archive
• Drange, Nina; Zachrisson, Henrik Daae; Almås, Ingvild & Meghir, Costas (2026). Early Childcare Attendance and Cognitive skills in Adolescence. National Bureau of Economic Research. Full text in Research Archive Show summary

  This paper examines the impact of early childcare on academic achievement for children in grade 5 and grade 9, based on a 2003 policy expansion that created quasi-random variation in slot availability for children aged 1–2. Starting childcare one year earlier increases math scores by 9.7% of a standard deviation (SD) in grade 9. Children whose mothers do not hold a high school diploma benefit by a significant 28% of a SD at grade 9, reducing the math achievement gap from children of higher-educated mothers by about one third. We also present evidence of strong improvements for children of immigrants.

• Thoresen, Thor Olav; Vattø, Trine Engh & Zachrisson, Henrik Daae (2026). Reducing child poverty through cash or care. Statistisk sentralbyrå (SSB). doi: https:/www.ssb.no/inntekt-og-forbruk/inntekt-og-formue/artikler/skal-en-redusere-barnefattigdom-med-okt-barnetrygd-eller-gratis-barnehage. Full text in Research Archive Show summary

  De siste tiårenes økning i barnefattigdom har fått betydelig oppmerksomhet. I denne analysen retter vi søkelyset mot hvilke tiltak som er mest effektive i fattigdomsbekjempelsen for familier med barn i alderen 1–5 år – økte kontantytelser, som høyere barnetrygd, eller tiltak som gratis barnehage.

• Rege, Mari; Thijssen, Maximiliaan Willem Pierre & Zachrisson, Henrik Daae (2025). The Social Gradient in Social and Emotional Skills. OSF PREPRINTS. doi: 10.31219/osf.io/zux2a_v1. Full text in Research Archive Show summary

  Social and emotional skills are critical for children’s development and success in educationand work life. Despite their importance for human capital development, few studies haveexamined how these skills vary across socioeconomic backgrounds. Evidence of a socialgradient in social and emotional skills would highlight an additional factor contributing tothe persistence of socioeconomic disparities across generations. Using four large datasetsfrom Norway, we analyze the social gradient in a comprehensive set of social and emotionalskills throughout childhood (e.g. behavior problems, executive function, relationship skills).We standardize family income rank across datasets by using national population registrydata to define income tertile cutoffs. Our findings reveal a significant and consistent socialgradient across assessments, samples, and ages, underscoring its role in drivingintergenerational persistence in socioeconomic status.

• Borgen, Solveig Topstad; Borgen, Nicolai Topstad & Zachrisson, Henrik Daae (2024). Ethnic minorities in disadvantaged neighborhoods: Differential effects on educational outcomes. SocArXiv. doi: 10.31235/osf.io/y6krf. Full text in Research Archive
• Rege, Mari; Bøe, Tormod; Drange, Nina; Fløtten, Tone; Glemmestad, Hanne & Hugvik, Kjell [Show all 8 contributors for this article] (2023). En barndom for livet: Økt tilhørighet, mestring og læring for barn i fattige familier. Departementenes sikkerhets- og serviceorganisasjon. Full text in Research Archive

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