The Social Mobility of Siblings in Comparative Perspective (the SIBMOB project)
This project examines the social class mobility of siblings in more than ten countries with the hope of better understanding why some countries or more socially mobile than others.
(See summary in Danish below)
How come some siblings from the same family end up in different social class positions? This is a question that has yet to be fully answered by sociologists.
The EU-funded SIBMOB project will conduct a large-scale comparative study to review the class mobility of siblings. It will provide a novel statistical approach to analysing these family types. Specifically, it will identify how class mobility is generated and why societies differ in their class mobility patterns. It will furnish sociologists with a widely applicable statistical approach to such analysis, including describing how and explaining why they differ both within and between countries. The project will apply its novel approach to data on siblings born during the 20th century in 10 countries.
The project consists of three overall parts. In the first part, the project team will collect data from over 10 countries and merge them into a large database containing information on the mobility experiences of siblings. In the second part, the project team will develop a set of new statistical techniques for examining the social class mobility of siblings. In the third part, the project team will apply the new methods to the database to conduct a large-scale, comparative study of the social class mobility of siblings.
While sociologists studying how social class positions are passed on from parents to children emphasize the family as the basic theoretical unit of intergenerational transmission processes, the comparative literature on social class mobility has paid no attention to how and why siblings from the same family end up in the same or in different classes. Indeed, all existing class mobility studies examine the mobility of individuals, thereby neglecting the key question of how societal differences in class mobility patterns result from social processes operating at the level of families.
SIBMOB will fill this puzzling gap in the class mobility literature by developing a comprehensive approach to and conducting a large-scale comparative study of the class mobility of siblings. The project argues that insofar as we want to understand how class mobility is generated and why societies differ in their class mobility patterns, the total pattern of class mobility in a society needs to be viewed as a sum of different types of families with distinct class mobility patterns. SIBMOB offers a novel statistical approach to analyzing these family types, including describing how and explaining why they differ both within and between countries. The project hypothesizes that cross-national and temporal variation in class mobility results from institutional and sociodemographic factors affecting families’ overall mobility opportunities in a given society. In a comparative study, the project will apply its novel approach to data on siblings born during the 20th century in 10 countries to test this and related hypotheses about why countries, or different birth cohorts within countries, differ in their overall class mobility patterns.
Key outcomes of SIBMOB will be a deeper understanding of families’ role in mobility processes, a comprehensive statistical methodology with wide applicability, and new comparative evidence on class mobility that is much richer than the existing evidence.
Notice: All publications are Open Access and can be accessed via the links below.
2022
- Education and Social Fluidity: A Reweighting Approach – Kristian Bernt Karlson – Sociological Science 9, February 2022.
2023
- Marginal Odds Ratios: What They Are, How to Compute Them, and Why Sociologists Might Want to Use Them – Kristian Bernt Karlson and Ben Jann – Sociological Science 10, April 2023.
- How (Not) to Use Risk Ratios in Sociological Research – Kristian Bernt Karlson and Lincoln Quillian – Socius 9, July 2023.
2024
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Origins of Attainment: Do Brother Correlations in Occupational Status and Income Overlap? – Kristian Bernt Karlson and Jesper Fels Birkelund – European Sociological Review 40(3), 2024.
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Family Background Consistently Affects Economic Success Across the Life Cycle: A Research Note on How Brother Correlations Overlap Over the Life Course – Kristian Bernt Karlson – The British Journal of Sociology 75, 2024.
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Economic Returns to Reproducing Parents’ Field of Study – Jesper Fels Birkelund – The British Journal of Sociology 75, 2024.
2025
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Explained Variance in Two-Level Models: A New Approach – Anders Holm, Ben Jann and Kristian Bernt Karlson – Sociological Methodology 55, 2025.
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Decomposing Sibling Correlations: A New Measure of Group-Specific Intergenerational Persistence in Socioeconomic Outcomes – Kristian Bernt Karlson and Jung In – European Sociological Review 41(5), 2025.
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Family Background and Life Cycle Earnings Volatility: Evidence from Brother Correlations in Denmark, Germany, and the United States – Filippo Gioachin and Kristian Bernt Karlson – Social Forces 104(1), 2025.
2026
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Unequal Time Transfers: Between-Sibling Inequality in Older Parents’ Childcare Support in Korea – Jung In – Journal of Marriage and Family 88, 2026.
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Is College Really “the” Equalizer? New Evidence Addressing Unobserved Selection – Haowen Zheng, Robert Andersen, Anders Holm and Kristian Bernt Karlson – Sociological Science 13, 2026.
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Do Educational Opportunities Skip Generations? Evidence from Sibling and Cousin Correlations in the United States – Kristian Bernt Karlson – Research in Social Stratification and Mobility 105, 2026.
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Teacher Bias, Socioeconomic Inequality, and the Role of Academic Reputations: Evidence from a Grading Reform – Jesper Fels Birkelund – Sociology of Education, accepted for publication 2026, green open access here.
Software
- em: Generic EM Algorithm – Dongjie Wu – R package, CRAN, 2023.
- lnmor, ipwlogit and riflogit: Stata commands for the estimation of marginal odds ratios – Ben Jann and Kristian Bernt Karlson, 2023. Available from the SSC archive (type “ssc install lnmor” in Stata).
- twolevelr2: Stata command for explained variance in two-level models – Ben Jann, 2024.
The project is led by principal investigator Kristian Bernt Karlson, Professor of Sociology. Over the course of the project the team consisted of postdoctoral researchers Dongjie Wu (2021–2023), Jesper Fels Birkelund (2022–2023), Jung In (2023–2025) and Stephan Dochow-Sondershaus (2024–2026), and research assistant Serena Chow (2021–2022).
Two visiting PhD students joined the project: Kim Stienstra (Utrecht University) and Filippo Gioachin (University of Trento).
The project’s scientific advisory board consists of Florencia Torche (Princeton University), Richard Breen (University of Oxford), Irena Kogan (University of Mannheim), Jacques Hagenaars (Tilburg University), Carina Mood (Stockholm University) and Herman van de Werfhorst.
Projektet undersøger og sammenligner søskendes sociale mobiletsmønstre på tværs af ti lande. Formålet med projektet er at undersøge, hvorfor nogle lande er mere socialt mobile end andre med udgangspunkt i de forskellige forhold ved velfærdsstater og familier, som angiveligt påvirker mobiliteten mellem generationer i et samfund. Projektet (1) samler en række internationale forskningsdata om søskendes mobiletsmønstre i én stor, samlet database, (2) udvikler nye metoder til at studere disse mønstre på og (3) anvender disse data og metoder i et stort empirisk studium af søskendes mobiletsmønstre i ti lande. Læs mere om projektet. Universitsavisen har også en beskrivelse af projektet og projektets leder.
Funding
SIBMOB is funded by European Research Council (ERC Starting Grant).
Project: Social Class Mobility in Comparative Perspective: Bringing Siblings In (SIBMOB)
Period period: 1/2-2021 – 31/7-2026
Contact
Kristian Bernt Karlson
Department of Sociology
Email: kbk@soc.ku.dk
Phone: +45 35 32 15 88
Awards
PI Kristian Bernt Karlson received the following awards and recognitions during the project:
- The 2022 Raymond Boudon Award for Early Career Achievements in Sociology, European Academy of Sociology.
- The 2023 Leo Goodman Award for Significant Contributions to Sociological Methodology, Section on Methodology, American Sociological Association.
- The 2023 Innovation Award for the Karlson-Holm-Breen method, Section on Methodology, American Sociological Association.
- Elected Member of the European Academy of Sociology, 2025.