Erratum to: Asymptotic formulae for likelihood-based tests of new physics Glen Cowan, Kyle Cranmer, Eilam Gross and Ofer Vitells Eur. Phys. J. C, 73 7 (2013) 2501 Published online: 20 July 2013 DOI: 10.1140/epjc/s10052-013-2501-z