Upper panel: filling factors of the inactive models in the combination fits as a function of I_{Ca IRT} of the four active stars LP 733-099 (yellow dots), TYC 3529-1437-1 (blue crosses), GJ 360 (red pluses), and G 234-057 (magenta diamonds) are shown. Lower panel: same as in the upper panel for Ross 905 (blue crosses), EW Dra (red pluses), LP 743-031 (yellow dots), GJ 625 (magenta diamonds), BD+70 68 (black asterisks), Ross 730 (cyan triangles), and GJ 793 (green circles). The solid lines show the linear fits of the stars. To improve clarity, the errors of I_{Ca IRT} are not shown.