Factor of improvement in the RV rms from the subtraction of the RV estimated from the RV-CRX correlation for each star in the CRX-all sample. Filled points indicate Hα active stars while open points show Hα inactive stars. Symbols are coloured based on CRX-gradient value or none (grey points). The factor of improvement is shown as a function of Pearson’s r (see Table 5 for parameters of the fit), stellar rotation period (upper row, left and right), stellar TiO7050 max-min value (using 95% percentiles) and normalised Hα luminosity (middle row left and right) and CRX-length/v sin i and (zoomed) spot contrast ratio (lower row, left and right). The stars are labelled as in Table A.1.