Scientific Reports 4, Article number: 5604 (2014); Published: 15 July 2013; Updated: 29 August 2014

There is a typographical error in the ‘Proximity’ section of this Article. “We repeated our analyses using time windows of various widths and found the results to be remarkably.” should read “We repeated our analyses using time windows of various widths and found the results to be remarkably robust”.