About the Authors
- Neff Walker, Fengmin Zhao
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- Kenneth Hill
- Harvard School of Public Health, Harvard University, Cambridge, Massachusetts, United States of America
The authors have declared that no competing interests exist.
Wrote the first draft of the manuscript: KH NW. Contributed to the writing of the manuscript: KH NW. ICMJE criteria for authorship read and met: NW KH FZ. Agree with manuscript results and conclusions: NW KH FZ. Conceived the analysis: NW. Collaborated on design of the analysis: KH. Performed the analysis: KH FZ. Analyzed the results: NW KH.