LTE (top left panel) and NLTE (other three panels) abundances from lines of Fe I (circles) and Fe II (triangles) in HD 122563 as a function of observed equivalent width W_obs. Top right panel: NLTE calculations with pure electronic collisions. Bottom row, left and right panels: YBK18+YBK19 and B18+YBK19 scenarios, respectively. In each panel, the dotted line indicates the mean abundance derived from the Fe I lines.