Left panels: rms of the residuals from the fit to the MOST light curve with a model of 30 active regions vs. four stellar parameters. Right panels: simulated RV curves resulting from the models compared to the SOPHIE data (red dots). The four pairs of panels show the dependence of the rms of the light curve fits and the RV signature on a) the zero point of the photometry; b) the stellar rotation period, P_rot; c) the facula-to-spot area ratio, Q; and d) the temperature contrast of the spots, ΔT_spot. The colour code of the lines in the right panels corresponds to the dots in the left panels.