Party Discipline, Representation, and the Condorcet Jury Theorem

Party Discipline, Representation, and the Condorcet Jury Theorem | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Party Discipline, Representation, and the Condorcet Jury Theorem Yves Kläy, Marco Portmann, David Stadelmann This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8262069/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract How does district size affect the quality of political representation? We examine a mechanism derived from the Condorcet Jury Theorem (CJT), which predicts that larger legislative delegations more accurately reflect constituents' preferences when individual legislators vote independently. However, nominal seat counts often overstate the number of independent decision-makers, because party discipline causes legislators’ votes to be correlated. We introduce effective district size as a measure that more accurately captures the number of independent politicians within a constituency. Using 263 Swiss referenda (1992-2024) matched to parliamentary decisions, we provide evidence in line with the CJT: the probability that a majority of a delegation reflects its constituents' preferences increases with (effective) district size. Crucially, the CJT aggregation mechanism accurately predicts delegation-constituency congruence only for effective, not nominal, district size. These results provide empirical evidence that the CJT applies to representative democracies and highlight how party discipline constrains the representative benefits of larger district sizes. JEL Classification: D72 , K16 , H11 representation district magnitude Condorcet Jury Theorem voting behavior party discipline legislative accountability Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8262069","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":558324148,"identity":"a0ac790e-e4db-4a7b-b111-0d3566aa5050","order_by":0,"name":"Yves Kläy","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4UlEQVRIiWNgGAWjYNCCAxZAgvkAA4OBHJDBQ5QWCSDBlgDUYkySFh4DIEGEFoMbyYc/MJyRkOeXyPkmXVBgkM/AfvYAAS1paRIMNyQMZ87I3SY9w8DAsoEnLwG/ljNnzBgYPkgwbrgB1MJj8MeAQQLsQnxazn/+ANRiv/9GzjOgFgMitBzvYQA5LHGDRA4bcVokj7eZSSSckUieceaZsTVICxtPDn4tfIeZH3/4cMzGtr89+eFtnj8GBvzsZ/BrUTgAJBJALIEEiAgbXvVAIN8AY/EfIKR2FIyCUTAKRioAAJNCQJ5H5cdyAAAAAElFTkSuQmCC","orcid":"","institution":"University of Fribourg","correspondingAuthor":true,"prefix":"","firstName":"Yves","middleName":"","lastName":"Kläy","suffix":""},{"id":558324150,"identity":"0fd9ae53-924c-48ea-ac85-b5b3f8c725f8","order_by":1,"name":"Marco Portmann","email":"","orcid":"","institution":"IWP Institute for Swiss Economic Policy","correspondingAuthor":false,"prefix":"","firstName":"Marco","middleName":"","lastName":"Portmann","suffix":""},{"id":558324152,"identity":"0a981903-621d-4a1a-a1d8-63307a588222","order_by":2,"name":"David Stadelmann","email":"","orcid":"","institution":"University of Bayreuth","correspondingAuthor":false,"prefix":"","firstName":"David","middleName":"","lastName":"Stadelmann","suffix":""}],"badges":[],"createdAt":"2025-12-02 15:08:26","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8262069/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8262069/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":97952927,"identity":"d452358a-6a3f-44ff-925a-f312db8c9cbb","added_by":"auto","created_at":"2025-12-11 07:24:28","extension":"json","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":4613,"visible":true,"origin":"","legend":"","description":"","filename":"31461f4f8c0145d89106cac6cb89f786.json","url":"https://assets-eu.researchsquare.com/files/rs-8262069/v1/50d04d60eb0540edc977a503.json"},{"id":97952939,"identity":"b02ac003-3c05-4fda-b510-9ee7812dcfc0","added_by":"auto","created_at":"2025-12-11 07:24:33","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":359149,"visible":true,"origin":"","legend":"","description":"","filename":"xjzjxwqmvfkdkhdqsgzwtvhtqhqqyfxh.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8262069/v1_covered_f5d8f136-ea92-4707-b625-6077cafff604.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Party Discipline, Representation, and the Condorcet Jury Theorem","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"representation, district magnitude, Condorcet Jury Theorem, voting behavior, party discipline, legislative accountability","lastPublishedDoi":"10.21203/rs.3.rs-8262069/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8262069/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHow does district size affect the quality of political representation? We examine a mechanism derived from the Condorcet Jury Theorem (CJT), which predicts that larger legislative delegations more accurately reflect constituents' preferences when individual legislators vote independently. However, nominal seat counts often overstate the number of independent decision-makers, because party discipline causes legislators’ votes to be correlated. We introduce effective district size as a measure that more accurately captures the number of independent politicians within a constituency. Using 263 Swiss referenda (1992-2024) matched to parliamentary decisions, we provide evidence in line with the CJT: the probability that a majority of a delegation reflects its constituents' preferences increases with (effective) district size. Crucially, the CJT aggregation mechanism accurately predicts delegation-constituency congruence only for effective, not nominal, district size. 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