Observed splittings (open symbols) for modes of degrees l = 1 (circles) and l = 2 (squares), plotted as a function of the parameter ζ, which indicates the trapping of the modes (a value of ζ closer to 0 indicates a p-dominated mode, whereas a value of ζ closer to 1 indicates a g-dominated mode). The dashed lines indicate linear regressions of the relation between the splittings of l = 1 modes and the parameter ζ. Gray symbols indicate suspicious measurements that were not taken into account (see text).