Potential conflicts of interest. K. E. W., L. F., and A. B. are employees and L. F. and A. B. are shareholders of Target RWE. J. K. E. reports grants or contracts from the National Institutes of Health (paid to the author’s institution), consulting fees from PLoS Medicine (paid to the author), and support for attending meetings and/or for travel from the Society for Epidemiologic Research (paid to the author); J. K. E. also had a leadership or fiduciary role on a committee for the Society of Epidemiologic Research (unpaid participation). All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.