“…Especially for LEWSs operating at regional scale (ReLEWSs), empirical evaluations are often carried out by simply analyzing the time frames during which significant high-consequence landslides occurred in the test area (Keefer et al, 1987;Baum and Godt, 2010;Capparelli and Tiranti, 2010;Aleotti, 2004). Alternatively, the performance evaluation is based on 2 by 2 contingency tables computed for the joint frequency distribution of landslides and alerts, both considered as dichotomous variables (Yu et al, 2003;Cheung et al, 2006;Godt et al, 2006;Restrepo et al, 2008;Tiranti and Rabuffetti, 2010;Kirschbaum et al, 2012;Martelloni et al, 2012;Peres and Cancelliere, 2012;Staley et al, 2013;Lagomarsino et al, 2013Lagomarsino et al, , 2015Greco et al, 2013;Segoni et al, 2014;Gariano et al, 2015;Stähli et al, 2015). The four elements of these tables -i.e., correct alerts (CAs) or true positives; missed alerts, false negatives or type II errors; false alerts, false positives or type I errors; true negatives (TNs) -are then used to assess the weight of the correct predictions in relation to the model errors by means of a series of statistical indicators of the model performance.…”