Updates are available Addendum dated 2014-08-27

Article History

Received: 15 October 2013

Accepted: 3 April 2014

First Online: 11 May 2014

Change Date: 8 August 2014

Change Type: Update

Change Details: In the Supplementary Information file for this Letter, the authors have added a section titled “Description of simulation procedure”, which provides a detailed account of the primary simulation procedure used in the study. This section is intended to allow others to directly replicate the results, and contains some detail and accompanying explanation omitted from the original version. The revised version also includes notational corrections to the proof of Proposition 1.

Competing interests

: The authors declare no competing financial interests.