The southern sky extrasolar planet search programme Coralie has today more than eight years 
of activity. The number of planets detections and measurments as well as the time baseline 
of the survey makes now possible a global statistical approach of the data. As a first step 
in this analysis, stellar spectra from the 1650 sources of the sample were re-reduced to 
compute the bisector velocity curve of the cross-correlation function. This indicator allow 
to detect the radial velocity variations due to stellar radial velocity jitter. By this way 
it's possible to better understand the limitation for planet detection induced by stellar 
activity.