[@Fukazawa:2011ly]). The significance of the effect was questioned by @Jimenez-Bailon:2005tg, who discussed the possible importance of contamination from radio-loud (RL) AGN, which have on average larger X-ray luminosities and smaller signatures of reprocessed radiation (e.g., [@Reeves:2000uq]). However, @Grandi:2006zr, studying [*BeppoSAX*]{} observations of radio-loud AGN, also found evidence of an X-ray Baldwin effect. This, together with the study of a large sample of radio-quiet (RQ) AGN carried out by @Bianchi:2007vn using [*XMM-Newton*]{} data, showed that the X-ray Baldwin effect is not a mere artifact. @Jiang:2006vn suggested that the X-ray Baldwin effect might be due to the delay between the variability of the AGN primary energy source and that of the reprocessing material located farther away. Using [*Chandra*]{}/HEG observations, @Shu:2010zr [@Shu:2012fk] confirmed the importance of variability, showing that averaging the values of $EW$ obtained over multiple observations of individual sources would significantly attenuate the anti-correlation from $EW \propto L_{\,\mathrm{X}}^{-0.18\pm0.03}$ to $EW \propto L_{\,\mathrm{X}}^{-0.11\pm0.03}$. [*Chandra*]{}/HEG observations [@Shu:2010zr] have also shown that the normalization of the X-ray Baldwin effect is lower (i.e. the average $EW$ of the narrow Fe K$\alpha$ component is smaller) with respect to that obtained by previous works performed using [*XMM-Newton*]{}. In Table\[tab:XBEref\] we report the values of the slope and 