Correction to: Palgrave Communications (2016) 2, Article number: 16026. doi: 10.1057/palcomms.2016.26; Published 17 May 2016; Updated 7 June 2016

In the version of this article originally published a number of elements of Fig. 4 were incorrectly rendered. The corrected Fig. 4 is shown below.

figure 1

Figure 4

The article has been corrected online.