Skin Deep: Educational Expansion, Phenotype, and the Mismeasurement of Inequality of Opportunity

Skin Deep: Educational Expansion, Phenotype, and the Mismeasurement of Inequality of Opportunity | 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 Skin Deep: Educational Expansion, Phenotype, and the Mismeasurement of Inequality of Opportunity Werner Hernani-Limarino This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9170981/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract A growing literature estimates inequality of opportunity (IOp) in education using the share of variance in years of schooling explained by circumstances of birth. This paper shows that this measure is mechanically contaminated by educational expansion whenever circumstances predict cohort composition. We derive an exact three-way decomposition of the standard IOp into a within-cohort component (genuine opportunity inequality), a between-cohort component (circumstances predicting cohort means), and a cross-term. Applying the schooling lag to Mexico's EMOVI 2023 (N = 16,514) with 10 circumstance dimensions, we find that 28% of the standard educational IOp is between-cohort artifact. The Shapley decomposition is systematically reshuffled: expansion-correlated circumstances (parental education +34%, childhood wealth +52%) are inflated, while within-cohort discrimination channels (skin color −38%, indigenous status −35%) are underweighted. Under the standard measure, childhood wealth's Shapley contribution is three times skin color's; after correction, they are equal. The bias is specific to years of schooling as the outcome: test-score IOp, income IOp, and binary-access IOp are either unaffected or affected through different mechanisms. The correction—regressing the schooling lag on circumstances instead of raw schooling—is simple and portable. JEL: D63 · I24 · J62 · C21 inequality of opportunity schooling lag educational expansion Shapley decomposition skin color Mexico EMOVI Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 27 Apr, 2026 Reviewers agreed at journal 13 Apr, 2026 Reviewers invited by journal 03 Apr, 2026 Editor assigned by journal 24 Mar, 2026 Submission checks completed at journal 24 Mar, 2026 First submitted to journal 19 Mar, 2026 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-9170981","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":618097877,"identity":"956f3b19-eef8-496c-a8af-6109292ad728","order_by":0,"name":"Werner Hernani-Limarino","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAyElEQVRIiWNgGAWjYPCCAzL8ICqhgAQtPJINIC0GpGgxOACiidFicLz32YOPe+7wGJ9fnfjhgQGDPL/YAQJazhw3N5zx7BmP2Y23myWADjOcOTsBvxazG2ls0jwHDgO1nN0A0pJgcJuQlvvP2KT/ALUYzzi7+QdxWm6wsUkzALUY8PduI84W+zNpbJI9QC0SN3i3WSQYSBD2i2T7MTaJHwcOy/H3n91880eFjTy/NAEtCCABVilBrHIQ4D9AiupRMApGwSgYSQAA195GO9lDrmMAAAAASUVORK5CYII=","orcid":"","institution":"Juno Foundation","correspondingAuthor":true,"prefix":"","firstName":"Werner","middleName":"","lastName":"Hernani-Limarino","suffix":""}],"badges":[],"createdAt":"2026-03-19 15:08:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9170981/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9170981/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106471367,"identity":"71d261a1-56d5-4351-a560-328380ebc112","added_by":"auto","created_at":"2026-04-09 01:46:12","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":221945,"visible":true,"origin":"","legend":"","description":"","filename":"Skindeep.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9170981/v1_covered_cf4d512e-45c3-4131-ade9-70dbea6c926e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Skin Deep: Educational Expansion, Phenotype, and the Mismeasurement of Inequality of Opportunity","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"the-journal-of-economic-inequality","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"joei","sideBox":"Learn more about [The Journal of Economic Inequality](http://link.springer.com/journal/10888)","snPcode":"10888","submissionUrl":"https://submission.nature.com/new-submission/10888/3","title":"The Journal of Economic Inequality","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"inequality of opportunity, schooling lag, educational expansion, Shapley decomposition, skin color, Mexico, EMOVI","lastPublishedDoi":"10.21203/rs.3.rs-9170981/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9170981/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA growing literature estimates inequality of opportunity (IOp) in education using the share of variance in years of schooling explained by circumstances of birth. 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