The Surrogate Index: Combining Short-Term Proxies to Estimate Long-Term Treatment Effects More Rapidly and Precisely.
A common challenge in estimating the impact of interventions (e.g. job training programmes, educational programmes) is that many outcomes of interest (e.g. lifetime earnings or other labour market outcomes) are observed with a long delay. In biomedical settings, this is often addressed by using shor...
| Publicado en: | Review of Economic Studies Vol. 93; no. 4; pp. 2284 - 2313 |
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| Autores principales: | , , , |
| Formato: | Artículo |
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Oxford University Press / USA
Jul2026
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ssf&AN=195161454&site=ehost-live header: @attributes: shortDbName: ssf uiTerm: 195161454 longDbName: Social Sciences Full Text (H.W. Wilson) uiTag: AN controlInfo: bkinfo: jinfo: jid: 00346527 REM jtl: Review of Economic Studies issn: 00346527 maglogo: N pubinfo: dt: Jul2026 vid: 93 iid: 4 pid: 622 pub: Oxford University Press / USA artinfo: ui: 195161454 10.1093/restud/rdaf087 ppf: 2284 ppct: 29 formats: tig: atl: The Surrogate Index: Combining Short-Term Proxies to Estimate Long-Term Treatment Effects More Rapidly and Precisely. aug: au: Athey, Susan Chetty, Raj Imbens, Guido W Kang, Hyunseung affil: Graduate School of Business, Stanford University and NBER, USA NBER and Department of Economics, Harvard University, USA Graduate School of Business, and Department of Economics, Stanford University, USA Department of Statistics, University of Wisconsin at Madison, USA su: Occupational training Treatment effectiveness Causal inference sug: subj: Occupational training Vocational Rehabilitation Services Treatment effectiveness Causal inference keyword: Causality copyrightHolder:Review of Economic Studies Ltd copyrightYear:2026 inLanguage:en Job training Mediators Potential outcomes Principal stratification Propensity score publisher:Oxford University Press sameAs:https://dx.doi.org/10.1093/restud/rdaf087 Surrogate index Surrogate outcomes Surrogate score Causality copyrightHolder:Review of Economic Studies Ltd copyrightYear:2026 inLanguage:en Job training Mediators Potential outcomes Principal stratification Propensity score publisher:Oxford University Press sameAs:https://dx.doi.org/10.1093/restud/rdaf087 Surrogate index Surrogate outcomes Surrogate score ab: A common challenge in estimating the impact of interventions (e.g. job training programmes, educational programmes) is that many outcomes of interest (e.g. lifetime earnings or other labour market outcomes) are observed with a long delay. In biomedical settings, this is often addressed by using short-term outcomes as so-called "surrogates" for the outcome of interest, e.g. tumour size as a surrogate for mortality in cancer studies. We build on this literature by combining multiple, possibly qualitatively distinct, short-term outcomes (e.g. short-run earnings and employment indicators) systematically into a "surrogate index". Under the Prentice surrogacy assumption, which requires that the primary outcome is independent of the treatment conditional on the surrogates, we show that the average treatment effect on the surrogate index equals the treatment effect on the long-term outcome. We also relate the surrogacy assumption to a set of structural, causal assumptions. We then characterize the bias that arises from violations of each of the key assumptions, and we provide simple methods to validate these assumptions using additional observed outcomes. We apply our method to analyse the long-term impacts of a multi-site job training experiment in California. Rather than waiting a full 9 years to directly observe the long-term impact, we show that it is possible to use short-term (the first six quarters) outcomes as surrogates. Given the surrogacy assumption one could have estimated the programme's long-term impacts on mean employment rates using the employment rates observed in the first six quarters, with a 35% reduction in standard errors relative to a simple difference in means estimator based on all 9 years of data. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: N holdings: @attributes: islocal: N |
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