Nicolai Borgen

Borgen, Nicolai; Haupt, Andreas & Wiborg, Øyvind (2026). A New Framework for Estimation of Unconditional Quantile Treatment Effects: The Residualized Quantile Regression (RQR) Model. Sociological methodology.

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. PNAS 123(15): e2537049123.

Cheesman, Rosa, Nicolai Borgen, Astrid Marie Jorde Sandsør, and Paul Hufe (2025). The Genetic Lottery Goes to School: Better Schools Compensate for the Effects of Students’ Genetic Differences. PNAS 122(43): e2511715122. 

Borgen, Nicolai Topstad & Zachrisson, Henrik Daae (2025). How neighborhood effects vary by achievement level. European Sociological Review 42(1): 215-231.

Borgen, Nicolai T., Andreas Haupt, and Øyvind Wiborg (2023). Quantile Regression Estimands and Models: Revisiting the Motherhood Wage Penalty Debate. European Sociological Review 39(2): 317-331. 

Borgen, Nicolai T, Solveig T. Borgen, and Gunn Elisabeth Birkelund (2023). The counteracting nature of contextual influences: Peer effects and offsetting mechanisms. Social Forces 101(3): 1288-1320.

• Borgen, Nicolai; Haupt, Andreas & Wiborg, Øyvind Nicolay (2026). A New Framework for Estimation of Unconditional Quantile Treatment Effects: The Residualized Quantile Regression (RQR) Model. Sociological methodology. ISSN 0081-1750. doi: 10.1177/00811750261450139. Full text in Research Archive Show summary

  The opportunities for understanding how treatment effects vary across different segments of the population have led to a rise in the use of quantile regressions for identifying unconditional quantile treatment effects (QTEs). However, existing quantile regression models fall into two categories: those that are unsuitable for identifying unconditional QTEs and those that often struggle with the complex data structures common in sociology and other social sciences. In particular, existing methods face difficulties with large data sets and high-dimensional fixed effects. The authors introduce a two-step approach to estimating unconditional QTEs, which is easy to use and aligns with the needs of sociologists. First, the treatment variable is decomposed into a systematic and random part, and then, the random variation in the treatment status is used as the sole independent variable in a quantile regression model. Through a series of simulations and three empirical applications, the authors provide strong evidence that the residualized quantile regression (RQR) approach provides approximately unbiased estimates of unconditional QTEs comparable with existing methods. Moreover, the RQR approach offers greater flexibility and enhances computational speed compared with existing models, and it can easily handle high-dimensional fixed effects. In sum, the RQR approach fills a pressing void in quantitative research methodology, offering a much-needed tool for studying treatment effect heterogeneity.

• Brodeur, Abel; Mikola, Derek; Cook, Nikolai; Fiala, Lenka; Brailey, Thomas & Briggs, Ryan [Show all 347 contributors for this article] (2026). Reproducibility and robustness of economics and political science research. Nature. ISSN 0028-0836. 652, p. 151–156. doi: 10.1038/s41586-026-10251-x. Full text in Research Archive Show summary

  Science aspires to be cumulative. Reproducibility efforts strengthen science by testing the reliability of published findings, promoting self-correction, and informing policy-making1. Computational reproductions, whereby independent researchers reproduce the results of published studies, are an essential diagnostic tool2–10. Such efforts should have greater visibility11–16. However, little social science reproduction and robustness has been conducted at scale10,13,17–23. Here we reproduced original analyses and conducted robustness checks of 110 articles that were published in leading economics and political science journals with mandatory data and code sharing policies17,18. We found that more than 85% of published claims were computationally reproducible. In robustness checks, our reanalyses showed that 72% of statistically significant estimates remain significant and in the same direction, and the median reproduced effect size is nearly the same as the originally published effect size (that is, 99% of the published effect size). Additionally, 6 independent research teams examined 12 pre-specified hypotheses about determinants of robustness. Research teams with more experience found lower levels of robustness, and robustness did not correlate with author characteristics or data availability. Robustness checks and reproduction of analyses with existing and updated data based on 110 articles in economics and political science journals with data and code-sharing requirements found high levels of robustness and reproducibility and determined that robustness was not dependent on author characteristics or data availability.

• 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.

• Braak, Dieuwer Ten & Borgen, Nicolai Topstad (2026). How associations between executive function and early academic skills may have been missed: A quantile regression approach. Early Childhood Research Quarterly. ISSN 0885-2006. 75, p. 201–213. doi: 10.1016/j.ecresq.2025.12.009. Full text in Research Archive Show summary

  This study uses residualized quantile regression modeling to investigate how aspects of executive function (self-regulation and working memory) differentially predict mathematics, vocabulary, and phonological awareness for children with various levels of these skills. This approach addresses the limitations of traditional linear regression, which overlooks variations in associations at different points in the skill distribution. The study utilized longitudinal data from 243 children (Mage = 5.79, 49% female), assessed in kindergarten and first grade. Self-regulation was measured with the Head-Toes-Knees-Shoulders task, and working memory with the Digit Span. The quantile regression findings indicate rather stable associations between self-regulation/working memory and mathematics for children across the mathematics proficiency distribution, largely reflecting traditional linear coefficients. However, traditional linear regression misses out on important associations with vocabulary and phonological awareness. That is, working memory predicted vocabulary specifically at the low end of the distribution across kindergarten and first grade, while both working memory and self-regulation’s predictive power for phonological awareness shifted from the high end of the distribution in kindergarten to the low end in first grade. The study highlights the importance of considering that executive function’s involvement in academic skills may fluctuate depending on the specific aspect of executive function, the child's developmental stage, and the type of academic skill. Quantile regression provides a nuanced understanding of these relationships, revealing that traditional linear regression may miss critical information. The findings suggest that interventions targeting executive function may be specifically beneficial for children who struggle with language and literacy skills, particularly in first grade.

• Brodeur, Abel; Borgen, Nicolai T.; Borgen, Solveig Topstad; Gugushvili, Alexi; Emirmahmutoglu, Aysil & Gavrilova-Zoutman, Evelina [Show all 7 contributors for this article] (2026). Comparing Human-Only, AI-Assisted, and AI-Led Teams on Assessing Research Reproducibility in Quantitative Social Science. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 123(22). doi: 10.1073/pnas.2524747123. Full text in Research Archive Show summary

  Large Language Models (LLMs) such as ChatGPT are transforming how scientists conduct and validate research, offering promise as tools to improve scientific reproducibility. However, computational reproducibility and error detection remain expensive and labor-intensive. We experimentally test how collaboration between researchers and LLM assistants influences the reproduction of quantitative social science findings across different levels of AI autonomy. We randomly assigned 288 researchers to 103 teams working under three conditions: human-only, AI-assisted (using ChatGPT as a collaborative tool), or AI-led (ChatGPT operating with minimal human oversight). Teams reproduced published results from leading social science journals, detected coding errors, and proposed robustness checks. Human-only and AI-assisted teams achieved comparable reproduction rates (94% vs. 91%) and performed similarly on most outcomes, except human-only teams identified significantly more major coding errors. Both substantially outperformed AI-led teams, which achieved only a 37% reproduction rate, detected fewer errors across all categories, proposed weaker robustness checks, and required more time. This autonomous approach, however, likely represents only a lower bound of AI capabilities. Despite rapid model advances, expert human judgment currently remains indispensable for reliable empirical verification. While AI assistance did not degrade most outcomes, it provided no measurable advantages and was associated with reduced detection of major errors. However, the 37% autonomous reproduction rate indicates that AI could provide value in settings where scale or cost constraints preclude human review of papers, even though general-purpose LLMs offer no immediate advantages for human-supervised verification.

• Borgen, Nicolai T. & Reimer, David (2025). Field of study choice and labor market outcomes. In Wolbers, Maarten H.J. & Verhaest, Dieter (Ed.), Handbook of Education and Work. Edward Elgar Publishing. ISSN 9781035309900. p. 52–74. doi: 10.4337/9781035309917.00009. Full text in Research Archive Show summary

  This chapter presents and discusses the relevant literature on field of study choice and labor market outcomes. It extends across multiple disciplines, including sociology and economics, and emphasizes important methodological advancements in measuring and quantifying the impact of field of study choices. The theoretical framework for why labor market outcomes differ between graduates from different fields is outlined. The chapter also examines the role of field of study choice as a process of horizontal differentiation that may potentially exacerbate labor market inequality. Subsequently, methods for identifying causal effects of fields of study are reviewed, followed by a discussion of the methodological challenges in measuring fields of study in applied quantitative work. Next, the existing empirical literature on field of study effects is reviewed. To illustrate the relevance of field of study choices, the authors present an applied example utilizing recent Norwegian administrative data. Finally, the chapter concludes with a summary of key developments over the past decades and outlines potential directions for future research.

• Borgen, Nicolai T.; Hermansen, Are Skeie & Sandsør, Astrid Marie Jorde (2025). Who Climbs the Ivory Tower? Social Origins of Academic Faculty in an Egalitarian Welfare State. Socius: Sociological Research for a Dynamic World. 11. doi: 10.1177/23780231251377209. Full text in Research Archive Show summary

  Although there is an extensive literature on intergenerational mobility in education, including the completion of PhD degrees, far less is known about the transition into academic faculty positions. Here, the authors use administrative microdata following entire birth cohorts born from 1955 to 1985 in Norway, an egalitarian welfare state, to investigate the social origins of academic faculty. Despite publicly funded higher education and competitive wages for PhD positions, arguably removing many barriers to entry, the present findings reveal persistent disparities in the likelihood of becoming a faculty member. Differences in earlier stages of the educational career largely account for these disparities, indicating that disadvantaged family background does not appear to constitute an additional barrier to becoming a faculty member when comparing individuals with PhD degrees. However, more advantageous social origins influence the likelihood of employment at more prestigious institutions and higher earnings among faculty members, indicating that socioeconomic origins impact academic careers beyond their effects on entering academia. Overall, these findings show that within an egalitarian context designed to promote equality of opportunity, social origins continue to shape access and progression within academia.

• Cheesman, Rosa Catherine Gillespie; Borgen, Nicolai T.; Sandsør, Astrid Marie Jorde & Hufe, Paul (2025). The Genetic Lottery Goes to School: Better Schools Compensate for the Effects of Students' Genetic Differences. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 122(43). doi: 10.1073/pnas.2511715122. Full text in Research Archive Show summary

  In this paper, we investigate whether better schools can compensate for the effects of children’s genetic differences. To this end, we combine data from the Norwegian Mother, Father, and Child Cohort Study (MoBa) with Norwegian register data to estimate the interaction between measures of children’s predisposition to education and school quality. We use MoBa’s genetic data to compute polygenic indices for educational attainment (PGIEA). Importantly, MoBa includes genetic data on mother-father-child trios, allowing us to identify causal genetic effects using within-family variation. We calculate school value-added measures from Norwegian register data, allowing us to causally estimate school quality effects. Leveraging the advantages of both data sources, we provide a causally identified study of gene–environment interactions in the school context. We find evidence for substitutability of PGIEA and school quality in reading but not numeracy: A 1 SD increase of school quality decreases the impact of a 1 SD increase of PGIEA on reading test scores by 6%. The substitutability arises through gains of students at the lower end of the PGIEA distribution. This suggests that investments in school quality may help reduce educational inequalities arising from genetic differences between students.

• Brini, Elisa; Borgen, Solveig Topstad & Borgen, Nicolai T. (2025). Avoiding the eyeballing fallacy: Visualizing statistical differences between estimates using the pheatplot command. The Stata Journal. ISSN 1536-867X. 25(1), p. 77–96. doi: 10.1177/1536867x251322962. Full text in Research Archive Show summary

  Graphical representations of coefficients and their confidence intervals are increasingly used in research presentations and publications because they are easier and quicker to read than tables. However, in coefficient plots that include several estimated coefficients, researchers often use confidence intervals to eyeball whether coefficients are statistically significant from each other, which results in an overly conservative test and increased risk of type II errors. To help avoid this eyeballing fallacy, we introduce the pheatplot postestimation command, which visualizes the statistical significance across estimates of categorical variables in a regression model. pheatplot efficiently compares the significance level between point estimates and helps researchers avoid making wrong assumptions about whether estimates differ. Moreover, by representing p -values as continuous measures rather than binary thresholds, it provides the flexibility to move beyond arbitrary cutoffs of statistical significance. This article offers some examples that illustrate the functionality of the pheatplot command.

• 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.

• Borgen, Nicolai T.; Kirkebøen, Lars Johannessen; Kotsadam, Andreas & Raaum, Oddbjørn (2025). Do funds for more teachers improve student outcomes? The Journal of human resources. ISSN 0022-166X. doi: 10.3368/jhr.0523-12892R2. Full text in Research Archive Show summary

  We investigate the effects of a large-scale Norwegian intervention that provided extra teachers to 166 lower secondary schools with relatively high student-teacher ratios and low average grades. We exploit these two margins using a regression discontinuity setup and find that the intervention reduced the student-teacher ratio by around 10%, without crowding out other school resources. The extra funding did not improve test scores and medium-term academic outcomes, and we can reject even small positive effects. We do find that more teachers improved the school environment, including self-reported student well-being, but with the largest impact on aspects of the school environment most weakly associated with better academic outcomes.

• 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.

• Brodeur, Abel; Mikola, Derek; Cook, Nikolai; al, . et; Andersen, Synøve Nygaard & Borgen, Nicolai T. [Show all 11 contributors for this article] (2024). Mass Reproducibility and Replicability: A New Hope. I4R Discussion Paper Series, The Institute for Replication (I4R). ISSN 2752-1931. Full text in Research Archive
• Borgen, Nicolai Topstad; Hermansen, Are Skeie & Sandsør, Astrid Marie Jorde (2024). Who Climbs the Ivory Tower? Social origins of academic faculty in an egalitarian welfare state. SocArXiv. doi: 10.31235/osf.io/c4xqz. Full text in Research Archive
• 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
• Borgen, Nicolai T.; Frønes, Ivar & Raaum, Oddbjørn (2023). Every tenth child: Heterogeneity in characteristics and life-course patterns among children in contact with child welfare services. Children and Youth Services Review. ISSN 0190-7409. 155, p. 1–10. doi: 10.1016/j.childyouth.2023.107308. Full text in Research Archive Show summary

  Every tenth Norwegian child has been in contact with the child welfare services (CWS) before age 18. This paper describes the variation in background characteristics of CWS children with different types of services and their life-course patterns from ages 10 to 25, compared to other children. We use high-quality population-wide Norwegian register data, covering about 860 000 children from birth cohorts 1987–2001, of which roughly 85 000 have received a CWS initiative. CWS children typically have lower socioeconomic backgrounds than other children. In terms of individual outcomes, they are more likely to have a criminal charge, be prescribed drugs for mental health and ADHD, fail in the educational system, and experience labor market marginalization. However, the heterogeneity among CWS children receiving different initiatives is more pronounced than dif- ferences between those in contact and those not. Adolescents with multisystemic therapy (MST) have the most unfavorable life-course patterns, in line with children in childcare institutions. Still, MST youth enter CWS late and have an advantaged family background compared to other CWS children, suggesting that individual-level risk factors are particularly important for sorting into MST.

• Borgen, Nicolai T.; Markussen, Simen & Raaum, Oddbjørn (2023). Socioeconomic differences in the long-term effects of teacher absence on student outcomes. European Societies. ISSN 1461-6696. 26(3), p. 639–667. doi: 10.1080/14616696.2023.2212744. Full text in Research Archive Show summary

  School teachers’ sickness absence has been shown to affect student achievement in the short run. However, we know little about whether socioeconomic backgrounds may compensate for reductions in instructional quality and to what extent teacher absence effects persist over time. This paper examines the socioeconomic differences in the short- and long-term effects of teacher absence. We use population-wide Norwegian register data to study the effects of certified teacher absence during lower secondary school (grades 8–10) on non-completion of upper secondary education by age 21 (i.e. school dropout) as well as academic achievement in 10th grade. In a school fixed effects model, we find that an increase in teacher absence of 5 percentage points reduces students’ examination grades by 2.3% of a standard deviation and increases the dropout probability by 0.6 percentage points. However, the teacher absence effects vary considerably by family background, with large effects for low-SES students driving the overall effects. Overall, our findings indicate that reductions in instructional quality increase social inequality in long-term educational outcomes. This result highlights that studying heterogeneous impacts of contextual exposures is needed to understand the role of schools in shaping inequality.

• Andersen, Synøve Nygaard; Borgen, Nicolai T.; Borgen, Solveig Topstad; Brini, Elisa; Frith, Michael James & Gugushvili, Alexi (2023). Replicating" State Action to Prevent Violence against Women". A Comment on Córdova & Kras (2022). I4R Discussion Paper Series, The Institute for Replication (I4R). ISSN 2752-1931. Full text in Research Archive
• Brini, Elisa; Borgen, Solveig Topstad & Borgen, Nicolai T. (2023). Avoiding the eyeballing fallacy: Visualizing statistical differences between estimates using the pheatplot command. SocArXiv. doi: 10.31235/osf.io/fghcd. Full text in Research Archive
• 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.

• Borgen, Nicolai T.; Borgen, Solveig Topstad & Birkelund, Gunn Elisabeth (2022). The Counteracting Nature of Contextual Influences: Peer Effects and Offsetting Mechanisms in Schools. Social Forces. ISSN 0037-7732. 101(3), p. 1288–1320. doi: 10.1093/sf/soac023. Full text in Research Archive Show summary

  There is currently a mismatch between the theoretical expectations of peer effects held by many scholars and the quantitative empirical literature. This paper contributes to the understanding of peer effects by highlighting the oft-overlooked conceptual distinction between social influences and a well-defined causal effect; peers may influence one another via several potentially contradicting mechanisms that result in small overall causal peer effects on educational outcomes. We exploit the idiosyncratic variation in gender composition across cohorts within schools to study offsetting mechanisms. Using population-wide Norwegian register and survey data, we find two distinct ways in which the share of girls in lower secondary schools (grades 8–10) affects academic outcomes. First, more girl peers improve the learning environment at school. Simultaneously, however, more girl peers reduce the students’ motivation for schoolwork. Such results suggest that peer effects stem from a complex process where various mechanisms are at odds with one another, and where the influence of peers on academic outcomes is a composite of different mechanisms. Overall, we find that more girl peers lower students’ school grades and reduce students’ likelihood of attending an academic track in upper secondary school (which qualifies for higher education). Supplementary analyses suggest that the achievement level of girls is the main reason for the gender peer effects found in our study.

• 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.

• Borgen, Nicolai Topstad; Haupt, Andreas & Wiborg, Øyvind (2022). Quantile regression estimands and models: revisiting the motherhood wage penalty debate. European Sociological Review. ISSN 0266-7215. 39(2), p. 317–331. doi: 10.1093/esr/jcac052. Full text in Research Archive Show summary

  This paper discusses the crucial but sometimes neglected differences between unconditional quantile regression (UQR) models and quantile treatment effects (QTE) models. We argue that there is a frequent mismatch between the aim of the quantile regression analysis and the quantitative toolkit used in much of the applied literature, including the motherhood wage penalty literature. This mismatch may result in wrong conclusions being drawn from the data, and in the end, misguided theories. In this paper, we clarify the crucial conceptual distinction between influences on quantiles of the overall distributions, which we term population-level influences, and individual-level QTEs. Further, we use data simulations to illustrate that various classes of quantile regression models may, in some instances, give entirely different conclusions (to different questions). Finally, we compare quantile regression estimates using real data examples, showing that UQR and QTE models differ sometimes but not always. Still, the conceptual and empirical distinctions between quantile regression models underline the need to match the correct model to the specific research questions. We conclude the paper with a few practical guidelines for researchers.

• 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.

• Borgen, Nicolai T.; Olweus, Dan; Breivik, Kyrre; Kirkebøen, Lars Johannessen; Solberg, Mona Elin & Frønes, Ivar [Show all 8 contributors for this article] (2022). Do School-Level Anti-Bullying Interventions Affect Prescriptions of Prescribed Drugs in Young Adulthood? A Case Using the Olweus Bullying Prevention Program. International Journal of Bullying Prevention. ISSN 2523-3653. 6(3), p. 188–188. doi: 10.1007/s42380-022-00150-w. Full text in Research Archive Show summary

  Several meta-analyses have demonstrated that bullying prevention programs are successful in reducing bullying. However, scant research addresses if and how such anti-bullying efforts affect long-term internalizing health problems and even less on later use of pharmacotherapy and psychotherapy. This study explores how the school-based Olweus Bullying Prevention Program (OBPP) affects the likelihood of being prescribed antidepressant drugs, anxiolytics, hypnotics, and sedatives, using a difference-in-difference design with population-wide Norwegian register data, including the Norwegian Prescription Database. Generally, we find that student cohorts from schools with a higher proportion of victimized students have more prescribed drugs at ages 17–22. Although OBPP substantially reduces victimization, and, hence, assumedly internalizing problems, our results indicate that the OBPP increased the likelihood of being prescribed drugs for internalizing problems between ages 17 and 19. Our interpretation of these findings is that the OBPP had increased awareness of bullying in school and its damaging consequences, and thereby reduced the mental and attitudinal barriers that often prevent students from seeking help for internalizing problems. It should be noted, however, that the victimization data in our study were linked to schools only and not to register data for individual students. Accordingly, we were restricted to studying average program effects at the school level. The power to detect long-term effects would have been better with student-linked data for both the victimization and register variables.

• Borgen, Nicolai Topstad; Raaum, Oddbjørn; Kirkebøen, Lars Johannessen; Sørlie, Mari-Anne; Ogden, Terje & Frønes, Ivar (2021). Heterogeneity in Short- and Long-Term Impacts of School-Wide Positive Behavior Support (SWPBS) on Academic Outcomes, Behavioral Outcomes, and Criminal Activity. Journal of Research on Educational Effectiveness. ISSN 1934-5747. 14(2), p. 409–409. doi: 10.1080/19345747.2020.1862375. Full text in Research Archive Show summary

  To address social and behavioral problems in schools, more than 26,000 schools around the world have implemented School-Wide Positive Behavior Support (SWPBS). Previous studies have focused on the effects of SWPBS on short-term teacher-rated behavior such as office discipline referrals or academic outcomes, but no study has yet investigated effects on long-term student outcomes. We use population-wide longitudinal register data, including all Norwegian students that are exposed to SWPBS, and examine effects on short- and long-term academic outcomes, as well as long-term school behavior and youth crime. Both when we evaluate average program effects for all students and when looking at at-risk students only, we find no indications that the Norwegian SWPBS affected any of these outcomes.

• Borgen, Nicolai Topstad; Olweus, Dan; Kirkebøen, Lars Johannessen; Breivik, Kyrre; Solberg, Mona Elin & Frønes, Ivar [Show all 8 contributors for this article] (2021). The Potential of Anti-Bullying Efforts to Prevent Academic Failure and Youth Crime. A Case Using the Olweus Bullying Prevention Program (OBPP). Prevention Science. ISSN 1389-4986. 22(8), p. 1158–1158. doi: 10.1007/s11121-021-01254-3. Full text in Research Archive Show summary

  The effectiveness of bullying prevention programs has led to expectations that these programs could have effects beyond their primary goals. By reducing the number of victims and perpetrators and the harm experienced by those affected, programs may have longer-term effects on individual school performance and prevent crime. In this paper, we use Norwegian register data to study the long-term impact of the Olweus Bullying Prevention Program (OBPP) on academic performance, high school dropout, and youth crime for the average student, which we call population-level effects. The OBPP program is widely acknowledged as one of the most successful programs reducing school-level bullying; yet, using a difference-in-difference design, no statistically significant population-level effects of the OBPP were found on any of the long-term outcomes in this study. When studied at the population level, as in the current project, the base rate prevalence of bullying is a major explanatory factor for these results. Earlier studies have shown that OBPP reduces bullying prevalence by 30–50%. This decrease translates into absolute reductions in bullying victimization and perpetration at the population level of “only” four and two percentage points, respectively. Our results suggest the average causal effects of school bullying involvement are too small to translate this reduction in bullying into a sizeable population-level impact on students’ long-term outcomes. However, a limited potential of anti-bullying programs to prevent population- level adversity can very well be compatible with substantial program effects for individual bullies and victims. Further, our results do not speak to the main objective of anti-bullying programs of limiting childhood abuse and safeguarding children’s human rights.

• Borgen, Nicolai T.; Frønes, Ivar & Raaum, Oddbjørn (2021). Impact of the School Environment on Medical Treatment of Attention Deficit Hyperactivity Disorder: A Population‐Wide Register Data Study of School‐Wide Positive Behavioral Interventions and Supports. Child Development. ISSN 0009-3920. 92(5), p. 2105–2105. doi: 10.1111/cdev.13574. Full text in Research Archive Show summary

  Although attention deficit hyperactivity disorder (ADHD) is among the most heritable psychiatric childhood disorders, social and gene–environment interactions seemingly play an important role in the etiology of ADHD. Consistent with this, this study finds that School‐Wide Positive Behavioral Interventions and Supports (SWPBIS) reduced the likelihood of pharmacotherapeutic treatment for ADHD at age 14–16 by 12%, using population‐wide Norwegian register data and a difference‐in‐difference design ( N  = 698,364, birth cohorts 1990–2002, 48.7% girls, 5.7% immigrant background). At‐risk students in schools with high fidelity of implementation are driving these intervention effects. Overall, the findings indicate that children with a genetic disposition for ADHD are more likely to avoid medical treatment in an organized and predictable school setting with a focus on positive reinforcement.

• Hermansen, Are Skeie; Borgen, Nicolai Topstad & Mastekaasa, Arne (2020). Long-term trends in adult socio-economic resemblance between former schoolmates and neighbouring children. European Sociological Review. ISSN 0266-7215. doi: 10.1093/esr/jcz066. Full text in Research Archive Show summary

  Abstract Schools and residential neighbourhoods constitute key contexts of development beyond the family of origin. Yet, few prior studies address whether the overall impact of these childhood contexts on adult life chances has changed over time. In this article, we investigate changes in socio-economic resemblance between former schoolmates and neighbouring children using Norwegian administrative data covering three decades. We use cross-classified multilevel models to decompose the variance in children’s educational attainment and adult earnings into the contributions found within and between their school and neighbourhood contexts in adolescence. We find that unadjusted school and neighbourhood correlations in educational attainment are relatively modest and declining over time. These trends largely reflect declining socio-economic segregation between schools and neighbourhoods over time. After adjusting for sorting by family background, schools account for 2 per cent or less of the total variation in completed years of education in the more recent cohorts and neighbourhoods even less. For adult earnings, the adjusted school correlations are very low, accounting for around 1 per cent of the total variance, while the contribution of neighbourhoods is close to zero. Our findings suggest that adolescent school and neighbourhood contexts are not major determinants of children’s later-life socio-economic attainments in the Norwegian welfare state setting.

• Borgen, Nicolai T.; Kirkebøen, Lars Johannessen; Ogden, Terje; Raaum, Oddbjørn & Sørlie, Mari-Anne (2019). Impacts of school‐wide positive behaviour support: Results from National Longitudinal Register Data. International Journal of Psychology (IJP). ISSN 0020-7594. 55(S1), p. 15–15. doi: 10.1002/ijop.12575. Full text in Research Archive Show summary

  Problem behaviour in schools may have detrimental effects both on students' well‐being and academic achievement. A large literature has consistently found that school‐wide positive behaviour support (SWPBS) successfully addresses social and behavioural problems. In this paper, we used population‐wide longitudinal register data for all Norwegian primary schools and a difference‐in‐difference (DiD) design to evaluate effects of SWPBS on a number of primary and secondary outcomes, including indicators of externalising behaviour, school well‐being, pull‐out instruction, and academic achievement. Indications of reduced classroom noise were found. No other effects were detected. Analyses revealed important differences in outcomes between the intervention and control schools, independent of the implementation of SWPBS, and that a credible design like DiD is essential to handle such school differences.

• Borgen, Nicolai T. (2019). Collider bias (aka sample selection bias) in observational studies: why the effects of hyperandrogenism in elite women’s sport are likely underestimated. British Journal of Sports Medicine. ISSN 0306-3674. 54(12), p. 750–752. doi: 10.1136/bjsports-2018-100054. Full text in Research Archive Show summary

  The medical condition of hyperandrogenism has entered common parlance because the International Association of Athletics Federation (IAAF) decided to ban women with the condition from competing against women who have ‘normal’ levels of testosterone (see box 1). This paper argues that the two articles substantiating the IAAF’s regulation1 2 fail to prove that elevated levels of natural testosterone are causally linked to better sporting performance. By studying elite athletes both papers induce a collider stratification bias that attenuates the competitive advantage of testosterone—a little-known bias that often plagues studies of highly selective samples.

• Borgen, Nicolai T.; Kirkebøen, Lars Johannessen; Ogden, Terje; Raaum, Oddbjørn & Sørlie, Mari-Anne (2019). Impacts of school-wide positive behaviour support: Results from National Longitudinal Register Data. International Journal of Psychology (IJP). ISSN 0020-7594. 55(S1), p. 4–15. doi: 10.1002/ijop.12575. Full text in Research Archive Show summary

  Problem behaviour in schools may have detrimental effects both on students' well‐being and academic achievement. A large literature has consistently found that school‐wide positive behaviour support (SWPBS) successfully addresses social and behavioural problems. In this paper, we used population‐wide longitudinal register data for all Norwegian primary schools and a difference‐in‐difference (DiD) design to evaluate effects of SWPBS on a number of primary and secondary outcomes, including indicators of externalising behaviour, school well‐being, pull‐out instruction, and academic achievement. Indications of reduced classroom noise were found. No other effects were detected. Analyses revealed important differences in outcomes between the intervention and control schools, independent of the implementation of SWPBS, and that a credible design like DiD is essential to handle such school differences.

• Borgen, Nicolai T. & Mastekaasa, Arne (2018). Horizontal Stratification of Higher Education: The Relative Importance of Field of Study, Institution, and Department for Candidates’ Wages. Social Forces. ISSN 0037-7732. 97(2), p. 531–558. doi: 10.1093/sf/soy075. Full text in Research Archive Show summary

  Studies typically find large variation in labor market outcomes not only between educational levels, but also among individuals with a higher education. However, the importance of different types of horizontal divisions in higher education is mostly treated in separate literatures. In this paper, we use multilevel models and an outcome-based approach to investigate the relative importance of institution (college), department, and field of study in the Norwegian labor market. We find that the effects of field of study on wages are generally strong. The overall effects of institution are also quite large, but they emerge to a considerable extent at the level of departments; the effects of institution over and above the effects of department are small. We also show that the effects of horizontal divisions are greater at the graduate than at the undergraduate level, and that the effects of horizontal divisions increase over individuals’ work careers.

• Borgen, Nicolai T. (2017). Running Performance, VO2max, and Running Economy: The Widespread Issue of Endogenous Selection Bias. Sports Medicine. ISSN 0112-1642. p. 1–10. doi: 10.1007/s40279-017-0789-9. Full text in Research Archive Show summary

  Studies in sport and exercise medicine routinely use samples of highly trained individuals in order to understand what characterizes elite endurance performance, such as running economy and maximal oxygen uptake ( VO2max ). However, it is not well understood in the literature that using such samples most certainly leads to biased findings and accordingly potentially erroneous conclusions because of endogenous selection bias. In this paper, I review the current literature on running economy and VO2max , and discuss the literature in light of endogenous selection bias. I demonstrate that the results in a large part of the literature may be misleading, and provide some practical suggestions as to how future studies may alleviate endogenous selection bias.

• Borgen, Solveig Topstad & Borgen, Nicolai T. (2016). Student retention in higher education: Folk high schools and educational decisions. Higher Education. ISSN 0018-1560. 71(4), p. 505–523. doi: 10.1007/s10734-015-9921-7. Full text in Research Archive
• Borgen, Nicolai T. (2016). Fixed Effects in Unconditional Quantile Regression. The Stata Journal. ISSN 1536-867X. 16(2), p. 403–415. doi: 10.1177/1536867x1601600208. Full text in Research Archive
• Borgen, Nicolai T. (2015). Changes in the Economic Returns to Attending Prestigious Institutions in Norway. European Societies. ISSN 1461-6696. 17(2), p. 219–241. doi: 10.1080/14616696.2015.1009843. Full text in Research Archive
• Borgen, Solveig Topstad & Borgen, Nicolai T. (2015). Folk high schools and dropouts from upper secondary school: effects of non-academic investments in dropouts. School Effectiveness and School Improvement. ISSN 0924-3453. 26(2), p. 153–168. doi: 10.1080/09243453.2014.896384. Full text in Research Archive
• Borgen, Nicolai T. (2015). College quality and the positive selection hypothesis: The ‘second filter’ on family background in high-paid jobs. Research in Social Stratification and Mobility. ISSN 0276-5624. 39, p. 32–47. doi: 10.1016/j.rssm.2014.11.001. Full text in Research Archive
• Borgen, Nicolai (2014). College quality and hourly wages: Evidence from the self-revelation model, sibling models and instrumental variables. Social Science Research. ISSN 0049-089X. 48, p. 121–134. doi: 10.1016/j.ssresearch.2014.05.010. Full text in Research Archive
• Borgen, Nicolai T. (2013). Instrumentvariabler – en introduksjon for samfunnsforskere. Sosiologi i dag. ISSN 0332-6330. 43(3), p. 39–64. Full text in Research Archive
• Borgen, Nicolai Topstad (2012). Sammenhengen mellom karakterer og studentgjennomstrømning i høyere utdanning :. Søkelys på arbeidslivet. ISSN 1504-8004. 29(1/2), p. 111–129. Full text in Research Archive

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• Bjermeland, Monica; Borgen, Nicolai T. & Mamelund, Svenn-Erik (2025). Har akademia et skjult klasseproblem? [Radio]. Universitetspodden. 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
• 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
• Borgen, Nicolai T.; Kirkebøen, Lars Johannessen; Kotsadam, Andreas & Raaum, Oddbjørn (2022). Do Funds for More Teachers Improve Student Outcomes? SSB - Discussion papers. ISSN 0809-733X. Full text in Research Archive
• Borgen, Nicolai T.; Kirkebøen, Lars Johannessen; Kotsadam, Andreas & Raaum, Oddbjørn (2022). Hvilken betydning har ekstra lærere? Full text in Research Archive
• Raaum, Oddbjørn; Kotsadam, Andreas; Kirkebøen, Lars Johannessen & Borgen, Nicolai Topstad (2022). Do funds for more teachers improve student outcomes? Full text in Research Archive
• Kotsadam, Andreas; Borgen, Nicolai Topstad & Kirkebøen, Lars Johannessen (2022). Do funds for more teachers improve student outcomes? Full text in Research Archive
• Kotsadam, Andreas; Borgen, Nicolai Topstad & Kirkebøen, Lars Johannessen (2022). Do funds for more teachers improve student outcomes? 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. 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
• Borgen, Nicolai T.; Hermansen, Are Skeie; Lyngstad, Torkild Hovde & Ystrøm, Eivind (2020). Misvisende om utdanningsulikhet. Aftenposten (morgenutg. : trykt utg.). ISSN 0804-3116. Full text in Research Archive
• Borgen, Nicolai T.; Borgen, Solveig Topstad & Birkelund, Gunn Elisabeth (2019). The disadvantage of having high achieving peers: Gender gaps and the complex nature of gender peer effects. Full text in Research Archive
• Borgen, Nicolai T.; Borgen, Solveig Topstad & Birkelund, Gunn Elisabeth (2019). Why having better peers is not always a good thing: The complex nature of gender peer effects. Full text in Research Archive
• Borgen, Nicolai T.; Borgen, Solveig Topstad & Birkelund, Gunn Elisabeth (2019). The disadvantage of high-achieving peers: Gender gaps and the complex nature of gender peer effects. Full text in Research Archive
• Borgen, Nicolai T. & Wiborg, Øyvind N (2018). New tools, novel consequences: Testing unconditional quantile regression using simulated data. Full text in Research Archive
• 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

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