Time difference between the shock passage at L1 and the onset of the storm sudden commencement as a function of the host regions’ CMD at the time of the source eruption. Information stems from Tables 3 and 4. The solid blue line indicates the mean of the time difference and the purple-shaded area indicates the standard deviation around this mean. Dotted lines in each plot indicate the solar limbs (east/west for CMD = −90°/90°) and the central meridian (CMD = 0°). The linear (Pearson) and rank order (Spearman) correlation coefficients are also provided.