Radial velocity data phase-folded to the best-fit period of each of the four Keplerian curves used in the final modelling of HD 40307 after subtracting the effect of the remaining signals and the long-term drift. The error bars include the additional noise term (see text). The inactive data set is plotted using filled red circles, while for the active data set we chose lighter empty circles. This promptly shows that the dispersion around the model is largely caused by the active data set. The blue lines represent the 95-% highest density interval (HDI).