Author Contributions: Dr Volpp had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Volpp, Loewenstein.
Acquisition of data: Volpp, John, Norton, Fassbender
Analysis and interpretation of data: Volpp, John, Troxel, Loewenstein.
Drafting of the manuscript: Volpp, John, Loewenstein.
Critical revision of the manuscript for important intellectual content: Volpp, John, Troxel, Norton, Fassbender, Loewenstein.
Statistical analysis: Volpp, John, Troxel, Loewenstein.
Obtained funding: Volpp, Loewenstein.
Administrative, technical, or material support: Volpp, Norton, Loewenstein.
Study supervision: Volpp, Loewenstein.
Financial Disclosures: None reported.
Funding/Support: This work was supported by grant P30 AG12836 from the National Institute on Aging, the Boettner Center for Pensions and Retirement Security at the University of Pennsylvania, grant R24 HD-044964 from National Institute of Child Health and Development Population Research Infrastructure Program, all at the University of Pennsylvania, and grant 58-4000-70058 from the US Department of Agriculture, Economic Research Service, and the Hewlett Foundation.
Role of the Sponsor: Neither the sponsors nor the funders had any role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.
Additional Contributions: We thank Daniel McDonald, MS, Carnegie Mellon University, Pittsburgh, Pennsylvania, and Evan Robinson, BS, University of Waterloo, Waterloo, Ontario, Canada, for their assistance.