Example of a diagnostic plot used to analyse each output catalogue provided by the participants to the EMC. Each dot shows the δf value of a fitted galaxy, colour-coded by the b/t value from the original Egg catalogue (colour-bar on the right), as a function of the input true magnitude in the considered band. The black solid line is the running median of the distribution, which should be identically zero for a perfect fit. The dotted lines show the (positive and negative) 1 and 5 levels, used to compute the diagnostics described in the text and reported in the top left corner of the plot (see Sect. 4).