About the Authors

Robert Carroll

robert.carroll@bristol.ac.uk

Affiliation School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom

Chris Metcalfe

Affiliation School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom

David Gunnell

Affiliation School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: RC CM DG. Analyzed the data: RC. Wrote the paper: RC CM DG.