Two examples of the posterior predictive check performed simulating 300 count rate spectra starting from the best-fit parameters posterior distributions. Data points are the actual spectrum, with green and orange contours as 16th−84th and 1st−99th interquantile ranges representing the predictive power of the spectral model. Energy bins in which the observed data point was not compatible within the 1st−99th interquantile range of the predicted spectra from the best-fit models are shown in red.