Distribution of the ΔCstat of the analysed sources plotted against their synchrotron peak. The blue triangles represent the results for all the analysed sources, whereas the orange circles represent the sources favouring a log parabola fit, having ΔCstat > 2.7 and –1 < β < 1.5. The dotted lines represent the quartiles and median distribution for the two populations. As it can be seen, the sources best fitted with a log parabola model tend to have slightly larger synchrotron peak frequency.