doi:http://dx.doi.org/10.1017/psrm.2013.1, Published by Cambridge University Press 2013.
The authors would like to correct a mistake in the expression below.
The mistake is in expression 1. This reads

Whereas it should have read

Published online by Cambridge University Press: 08 November 2013
doi:http://dx.doi.org/10.1017/psrm.2013.1, Published by Cambridge University Press 2013.
The authors would like to correct a mistake in the expression below.
The mistake is in expression 1. This reads
Whereas it should have read