ACF for the whole XMM-LSS sample in the soft band for sources with HR  >  −0.2 (filled circles, hard-spectrum AGN), and for sources with HR  <  −0.2 (open circles; soft-spectrum AGN). Note that for clarity reasons we do not plot the w(θ) uncertainties of the later sources. The solid line represents the γ = 1.8 fit to the HR  >  −0.2 w(θ), while the dashed line corresponds to the HR  <  −0.2 w(θ) fit.