社会违约与计划选择：配偶追随案例（英）

Social Defaults and Plan Choice The Case of Spousal Following Tal GrossTim LaytonDaniel PrinzJulia Yates Economic Policy Global DepartmentSeptember 2025 Policy Research Working Paper11207 Abstract This paper studies how couples in the Medicare Part D pro-gram choose an insurance plan. Over 70 percent of enrolleeschoose the same plan as their spouse. Even among thosewith differing health care needs, well over half do so. Dis-crete- choice models suggest that beneficiaries place a valueof more than $1,000 per year on being on the same plan as their spouse. Using a regression-discontinuity design,the paper shows that younger spouses disproportionatelyfollow their older spouse’s plan choice. Joint plan choicecontributes modestly to overall overspending, but increasescosts substantially for couples with different cost-minimiz-ing plans. This paper is a product of the Economic Policy Global Department. It is part of a larger effort by the World Bank toprovide open access to its research and make a contribution to development policy discussions around the world. PolicyResearch Working Papers are also posted on the Web at http://www.worldbank.org/prwp. The authors may be contactedat dprinz@worldbank.org. The Policy Research Working Paper Series disseminates the findings of work in progress to encourage the exchange of ideas about developmentissues. An objective of the series is to get the findings out quickly, even if the presentations are less than fully polished. The papers carry thenames of the authors and should be cited accordingly. The findings, interpretations, and conclusions expressed in this paper are entirely thoseof the authors. They do not necessarily represent the views of the International Bank for Reconstruction and Development/World Bank andits affiliated organizations, or those of the Executive Directors of the World Bank or the governments they represent. Social Defaults and Plan Choice:The Case of Spousal Following∗ Tal Gross†Tim Layton‡Daniel Prinz§Julia Yates¶ JEL codesI13, H31Keywords:Health insurance choice, Social defaults, Spousal decision-making ∗We are grateful to Keith Ericson, Sandra Gain, Jim Rebitzer, ´Agnes Szab´o-Morvai, Roula Yazigi,and seminar participants at Lehigh University, Purdue University, Stanford University, the Univer-sity of Georgia, Georgia State University, the University of Ottawa, the University of Pennsylvania,the University of Virginia, the University of San Diego, the University of Duisburg-Essen, and theCERS Institute of Economics for useful feedback. Amanda Stiebris provided superb research assis-tance. Research reported in this publication was supported by the National Institute on Aging ofthe National Institutes of Health under Award Number P30AG012810 through the National Bureauof Economic Research Center for Aging and Health Research. The content is solely the responsibil-ity of the authors and does not necessarily represent the official views of the National Institutes ofHealth. The findings, interpretations, and conclusions expressed in this paper are entirely those ofthe authors. They do not represent the views of the World Bank and its affiliated organizations, orthose of the Executive Directors of the World Bank or the governments they represent.†Boston University and NBER, talgross@bu.edu ‡University of Virginia and NBER, timothyjlayton@virginia.edu§World Bank, dprinz@worldbank.org¶University of Michigan, jryates@umich.edu Default options guide many important economic decisions.Many consumers, forinstance, choose a retirement-savings plan passively by opting into whatever plan isthe default option (Madrian and Shea, 2001; Beshears et al., 2008). Similarly, manypeople choose whether or not to become organ donors based on whether or not theyare automatically enrolled in an organ-donation program (Johnson and Goldstein,2003). Other decisions require an active choice. Americans are not automatically assignedto a car insurer. They must choose one if they want to drive legally. In many contexts,the choice of a health insurance plan is similar:consumers are not automaticallyenrolled in a particular plan and so have to make an active choice among the plansoffered to them. Such active choices may facilitate better decisions (Carroll et al., 2009; Bernheimet al., 2015; Goldin and Reck, 2022).Without automatic enrollment in a defaultoption, perhaps consumers are forced to weigh all options equally and so are morelikely to choose the product that is best for them. Then again, the absence of a default option does not imply that consumers makesuch decisions in a vacuum.They may use heuristics to make these decisions.Inparticular, consumers observe the choices of their peers, and their peers’ choices mayact as a “social default.”1Instead of a social planner singling out a particular optionas the default, the choices of peers may act in a similar fashion. For complex products, social defaults may be problematic.It is one thing ifconsumers choose t