Interquartile range (IQR) of the [O/Na] ratio in NGC 362 as a function of the total absolute magnitude of the cluster (left panel) and of the maximum temperature along the HB (right panel). NGC 362 is represented by a filled star symbol. The filled square is for ω Cen from Johnson & Pilachowski (2010) and the filled triangle indicates M 54 (Carretta et al. 2010c). The other clusters are from Carretta et al. (2009a, 2011). In the left panel, the location of NGC 288 is indicated. In each panel, the Spearman rank correlation coefficient (r_s) and the Pearson’s correlation coefficient are reported.