- Correspondence to Dr Chris P Gale, Division of Biostatistics, School of Medicine, Level 8, Worsley building, University of Leeds, Clarendon Way, West Yorkshire, Leeds LS2 9JT, UK;
- Received June 27, 2013
- Revised December 10, 2013
- Accepted December 11, 2013
- First published January 16, 2014.
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