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How Social Networks Shape Our Beliefs: A Natural Experiment among Future French Politicians

Author

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  • Yann Algan

    (ECON - Département d'économie (Sciences Po) - Sciences Po - Sciences Po - CNRS - Centre National de la Recherche Scientifique, CEPREMAP - Centre pour la recherche économique et ses applications - ECO ENS-PSL - Département d'économie de l'ENS-PSL - ENS-PSL - École normale supérieure - Paris - PSL - Université Paris Sciences et Lettres)

  • Quoc-Anh Do

    (ECON - Département d'économie (Sciences Po) - Sciences Po - Sciences Po - CNRS - Centre National de la Recherche Scientifique, CEPR - Center for Economic Policy Research)

  • Nicolò Dalvit
  • Alexis Le Chapelain

    (ECON - Département d'économie (Sciences Po) - Sciences Po - Sciences Po - CNRS - Centre National de la Recherche Scientifique)

  • Yves Zenou

    (IFN - Research Institute of Industrial Economics)

Abstract
This paper shows how a public policy shapes convergence of beliefs through newly-formed social networks, with a focus on political opinion. We use a unique natural experiment that randomly assigns students into first-year groups at a French college that forms future top politicians. Pairs of students in the same group are much more likely to become friends. The randomized group membership serves as instrumental variable in a dyadic regression of differences in beliefs on friendship. We find that students' political opinions converge particularly strongly between friends, reaching 11% of a standard deviation only after 6 months. Convergence is strongest among pairs least likely to become friends without the randomized exposure, or friends whose characteristics are the most different. While there is evidence of homophily in network formation, it does not seem to affect the estimates of convergence, except among very similar friends. The same strategy shows that a longer network distance implies slower convergence.

Suggested Citation

  • Yann Algan & Quoc-Anh Do & Nicolò Dalvit & Alexis Le Chapelain & Yves Zenou, 2015. "How Social Networks Shape Our Beliefs: A Natural Experiment among Future French Politicians," SciencePo Working papers Main hal-03459820, HAL.
    • Handle: RePEc:hal:spmain:hal-03459820
    Note: View the original document on HAL open archive server: https://sciencespo.hal.science/hal-03459820
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    2. Quoc-Anh Do & Yen-Teik Lee & Bang Dang Nguyen, 2016. "Directors as Connectors: The Impact of the External Networks of Directors on Firms," Post-Print hal-03393196, HAL.
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    4. Abel FRANCOIS & Laurent WEILL & Nicolas EBER, 2022. "Economists are born and raised, not made," Working Papers of LaRGE Research Center 2022-07, Laboratoire de Recherche en Gestion et Economie (LaRGE), Université de Strasbourg.
    5. Zenou, Yves & Lindquist, Matthew & Sauermann, Jan, 2015. "Network Effects on Worker Productivity," CEPR Discussion Papers 10928, C.E.P.R. Discussion Papers.
    6. Maité Laméris & Pierre-Guillaume Méon & Anne-Marie Van Prooijen, 2019. "What have we done? The impact of choosing and studying different academic disciplines on beliefs and values," Working Papers CEB 19-007, ULB -- Universite Libre de Bruxelles.
    7. Lisa Windsteiger, 2018. "Sorting in the Presence of Misperceptions," Working Papers tax-mpg-rps-2018-08, Max Planck Institute for Tax Law and Public Finance.
    8. Francesco Drago & Friederike Mengel & Christian Traxler, 2020. "Compliance Behavior in Networks: Evidence from a Field Experiment," American Economic Journal: Applied Economics, American Economic Association, vol. 12(2), pages 96-133, April.
    9. Matthew O. Jackson & Brian W. Rogers & Yves Zenou, 2017. "The Economic Consequences of Social-Network Structure," Journal of Economic Literature, American Economic Association, vol. 55(1), pages 49-95, March.
    10. Maite D. Laméris & Pierre-Guillaume Méon & Anne-Marie Prooijen, 2023. "What have we done?! The impact of economics on the beliefs and values of business students," Journal of Business Economics, Springer, vol. 93(3), pages 433-483, April.
    11. Quoc-Anh Do & Yen-Teik Lee & Bang Dang Nguyen, 2016. "Directors as Connectors: The Impact of the External Networks of Directors on Firms," SciencePo Working papers Main hal-03393196, HAL.
    12. Lisa Windsteiger, 2018. "Monopolistic Supply of Sorting, Inequality and Welfare," Working Papers tax-mpg-rps-2018-15, Max Planck Institute for Tax Law and Public Finance.
    13. Matthew O. Jackson & Brian W. Rogers & Yves Zenou, 2016. "Networks: An Economic Perspective," Papers 1608.07901, arXiv.org.

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    More about this item

    Keywords

    Political Beliefs; Peers; Social Networks; Convergence; Homophily; Belief Transmission; Learning; Diffusion; Natural Experiment;
    All these keywords.

    JEL classification:

    • C93 - Mathematical and Quantitative Methods - - Design of Experiments - - - Field Experiments
    • D72 - Microeconomics - - Analysis of Collective Decision-Making - - - Political Processes: Rent-seeking, Lobbying, Elections, Legislatures, and Voting Behavior
    • Z13 - Other Special Topics - - Cultural Economics - - - Economic Sociology; Economic Anthropology; Language; Social and Economic Stratification

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