Upper panel: Kepler light curve of the star KIC 2714077. Vertical red lines indicate the quarters Q1-Q17. Red triangles at the bottom and the top show the 5th and 95th percentile of the intensity, respectively. For each quarter we measure the intensity difference between the upper and the lower triangle, which equals R_var. Middle panel: time series of the variability range R_var(t) of the same star, defined as the difference between the 5th and 95th percentiles in each quarter. Lower panel: time series of the rotation periods P_rot(t) of the same star. The red curve in the middle and lower panels show the best sine fit to the R_var(t) and P_rot(t) time series, respectively.