Pearson correlation coefficients for our sample of high excitation Seyfert 2s from the S7 survey. From bottom to top panel, the V band extinction in magnitudes A_V and the extinction corrected values of observed [Ar IV]+ (λ4711Å+/λ4740Å), [O III] (λ5007Å/λ4861Å) and R_OIII line ratios (Tables 1 and 2) versus the aperture D (in kpc) used to extract the spectra. The value of the Pearson correlation coefficient (P) is indicated in each panel. The red points identify the three outliers discussed in Sect. 3.5.