Dependence of the CRX-length as a function of Pearson’s r value (upper panel), spot contrast (middle panel), and rotation period (lower panel) for the CRX-all stars sample. Closed symbols indicate Hα active stars and open symbols Hα inactive stars. Points are coloured by projected stellar rotational velocity (v sin i). The CRX-slope stars are labelled as indicated in Table A.1. In the top panel, the two arrows indicate two stars with positive Pearson’s r correlation. Their true Pearson’s value is shown in the label for each point. The parameters of the fitted straight lines are summarised in Table 5.