All Student’s t tests of statistical significance at the 5% confidence level are one-sided, not two-sided as stated in the original article (Deser et al. 2017).
REFERENCE
Deser, C., I. R. Simpson, K. A. McKinnon, and A. S. Phillips, 2017: The Northern Hemisphere extratropical atmospheric circulation response to ENSO: How well do we know it and how do we evaluate models accordingly? J. Climate, 30, 5059–5082, https://doi.org/10.1175/JCLI-D-16-0844.1.