Correlation of the time interval, Δt_succ, between two successive RV measurements and their observed ΔRV_succ. Top: The black crosses represent measurements taken in this work and in Marchenko et al. (2007). Middle: Measurements of a simulated population of long-period binaries with orbital periods between 1 and 10 years (see the main text for details), shown as colored dots. For clarity, we show only 2 of the 100 000 simulated observing campaigns. Bottom: Histogram of the 100 000 fitted slopes. The two vertical lines indicate the values of the two examples shown in the middle panel.