Nowadays many attempts are made to establish a qualitative and a quantitative connection between Kuiper Belt Population and Jupiter Family Comets. Basically, this can be thought as a diffusion process throughout the outer Solar System due to multiple close encounters with the giant planets. But, following the path of a body in such a process is not an easy task to be approached analytically nor numerically, because the motion is very chaotic and spread over a long time. A statistical approach seems to be a reasonable way and is the purpose of this paper.