Median normalised bias between z_MUSE and pz_EAZY for three different IGM models. The solid black and dashed blue lines show the default EAZY IGM model and the IGM model using the I14 prescription respectively. The orange line with shading shows the adjusted IGM model with the jointly smallest bias at z = 3 and slope (see text for details). The shaded region shows the uncertainty on the median and this is suppressed for the blue and black lines as these are near identical to that shown for the orange line.