Histogram and box-and-whisker plots for the deviation between calculated valence level energies and recommended values in the NIST online database (Kramida et al. 2018) for the L-shell ions of Fe. Results are included only for the 205 level energies present in both (a) the present MR-MP calculations and (b) the CHIANTI v8 database (Dere et al. 1997; Del Zanna et al. 2015). The annotations show the statistical parameters determined using the method of Tukey (1977): first (Q1), second (Q2), and third (Q3) quartile; lower (LIF) and upper (UIF) inner fences; and lower (LOF) and upper (UOF) outer fences.