Scatter of the LAV RV time series of several sets of inactive lines for J07446+0355 (YZ CMi). The different line sets are selected by limiting the line RV scatter (wstdRV, y-axis) and the strength of the correlation between the line RV and an activity indicator (Pearson's correlation coefficient R, x-axis). Each data point corresponds to a different set of selected lines. The colour of the data points indicates the scatter of the average RV time series obtained for each line set. We show the results obtained using the correlation with three activity indicators: total RV of the spectrum (left), BIS (middle), and CRX (right). The data points highlighted in red indicate the datasets with the smallest RV time series scatter (values within 10% of the absolute minimum). The data point highlighted in orange indicates the initial dataset that uses all lines to compute the RV. The numbers in these points indicate the scatter obtained using these sets of lines (i.e. they reflect the colour of the data point).