{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T02:16:09Z","timestamp":1790648169187,"version":"4.1.0"},"reference-count":53,"publisher":"Oxford University Press (OUP)","issue":"5","license":[{"start":{"date-parts":[[2023,7,19]],"date-time":"2023-07-19T00:00:00Z","timestamp":1689724800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000006","name":"ONR","doi-asserted-by":"publisher","award":["N00014-17-1-2131 and N00014-19-1-2468"],"award-info":[{"award-number":["N00014-17-1-2131 and N00014-19-1-2468"]}],"id":[{"id":"10.13039\/100000006","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2024,2,2]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:p>We develop new semi-parametric methods for estimating treatment effects. We focus on settings where the outcome distributions may be thick tailed, where treatment effects may be small, where sample sizes are large, and where assignment is completely random. This setting is of particular interest in recent online experimentation. We propose using parametric models for the treatment effects, leading to semi-parametric models for the outcome distributions. We derive the semi-parametric efficiency bound for the treatment effects for this setting, and propose efficient estimators. In the leading case with constant quantile treatment effects, one of the proposed efficient estimators has an interesting interpretation as a weighted average of quantile treatment effects, with the weights proportional to minus the second derivative of the log of the density of the potential outcomes. Our analysis also suggests an extension of Huber\u2019s model and trimmed mean to include asymmetry.<\/jats:p>","DOI":"10.1093\/jrsssb\/qkad072","type":"journal-article","created":{"date-parts":[[2023,7,19]],"date-time":"2023-07-19T14:06:48Z","timestamp":1689775608000},"page":"1615-1638","source":"Crossref","is-referenced-by-count":11,"title":["Semi-parametric estimation of treatment effects in randomised experiments"],"prefix":"10.1093","volume":"85","author":[{"given":"Susan","family":"Athey","sequence":"first","affiliation":[{"name":"Graduate School of Business, Stanford University, CA , USA"},{"name":"National Bureau of Economic Research , MA , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peter J","family":"Bickel","sequence":"additional","affiliation":[{"name":"Department of Statistics, University of California , Berkeley, CA , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aiyou","family":"Chen","sequence":"additional","affiliation":[{"name":"Waymo , Mountain View, CA , USA"},{"name":"Google LLC , Mountain View, CA , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Guido W","family":"Imbens","sequence":"additional","affiliation":[{"name":"Graduate School of Business, Stanford University, CA , USA"},{"name":"National Bureau of Economic Research , MA , USA"},{"name":"Department of Economics, Stanford University, CA , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael","family":"Pollmann","sequence":"additional","affiliation":[{"name":"Department of Economics, Duke University , NC , USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2023,7,19]]},"reference":[{"key":"2024020300383004600_qkad072-B1","author":"Alvarez","year":"2022"},{"key":"2024020300383004600_qkad072-B2","author":"Alvarez","year":"2022"},{"issue":"3","key":"2024020300383004600_qkad072-B3","doi-asserted-by":"crossref","first-page":"847","DOI":"10.1214\/aoms\/1177700058","article-title":"On some robust estimates of location","volume":"36","author":"Bickel","year":"1965","journal-title":"The Annals of Mathematical Statistics"},{"key":"2024020300383004600_qkad072-B4","author":"Bickel","year":"1967"},{"key":"2024020300383004600_qkad072-B5","volume-title":"Mathematical statistics: Basic ideas and selected topics","author":"Bickel","year":"2015"},{"key":"2024020300383004600_qkad072-B6","author":"Bickel","year":"2012"},{"key":"2024020300383004600_qkad072-B7","volume-title":"Efficient and adaptive estimation for semiparametric models","author":"Bickel","year":"1993"},{"issue":"5","key":"2024020300383004600_qkad072-B8","first-page":"1038","article-title":"Descriptive statistics for nonparametric models I. 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