Background: The Moving To Opportunity (MTO) experiment manipulated neighborhood context by randomly assigning housing vouchers to volunteers living in public housing to use to move to lower poverty neighborhoods in five US cities. This random assignment overcomes confounding limitations that challenge other neighborhood studies. However, differences in MTO's effects across the five cities have been largely ignored. Such differences could be due to population composition (e.g., differences in the racial/ethnic distribution) or to context (e.g., differences in the economy). Methods: Using a nonparametric omnibus test and a multiply robust, semiparametric estimator for transportability, we assessed the extent to which differences in individual-level compositional characteristics that may act as effect modifiers can account for differences in MTO's effects across sites. We examined MTO's effects on marijuana use, behavioral problems, major depressive disorder, and generalized anxiety disorder among black and Latino adolescent males, where housing voucher receipt was harmful for health in some sites but beneficial in others. Results: Comparing point estimates, differences in composition partially explained site differences in MTO effects on marijuana use and behavioral problems but did not explain site differences for major depressive disorder or generalized anxiety disorder. Conclusions: Our findings provide quantitative, rigorous evidence for the importance of context or unmeasured individual-level compositional variables in modifying MTO's effects.
Bibliographical noteFunding Information:
Submitted February 8, 2017; accepted October 18, 2017. From the aSchool of Public Health, University of California, Berkeley, CA; bDepartment of Epidemiology and Community Health, University of Minnesota School of Public Health, Minneapolis, MN; and cDepartment of Epidemiology and Biostatistics, University of California, San Fran-cisco, CA. This work was supported in part by the National Institute on Drug Abuse (K99DA042127-01; PI: Rudolph). T.L.O., M.M.G., and N.M.S. were sup-ported by R01 MD006064. Data and analysis code: Researchers may apply for data access through ICPSR: http://www.icpsr.umich.edu/icpsrweb/ICPSR/studies/31661. Computing code required to replicate the results will be made available on the first author’s github page: https://github.com/cherrygarcia/MTO-site-transport-ability-paper-code/blob/master/submissioncode1.R. Disclosure: The authors report no conflicts of interest. Supplemental digital content is available through direct URL citations in the HTML and PDF versions of this article (www.epidem.com). Correspondence: Kara E. Rudolph, 13B University Hall, School of Public Health, Berkeley, CA 94720. E-mail: firstname.lastname@example.org Copyright 2017 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 1044-3983/18/2902-0199 DOI: 10.1097/EDE.0000000000000774