The mean distance to the <i>n</i> th neighbour in a uniform distribution of random points: an application of probability theory

Abstract

We study different ways of determining the mean distance rn between a reference point and its nth neighbour among random points distributed with uniform density in a D-dimensional Euclidean space. First, we present a heuristic method; though this method provides only a crude mathematical result, it shows a simple way of estimating rn. Next, we describe two alternative means of deriving the exact expression of rn: we review the method using absolute probability and develop an alternative method using conditional probability. Finally, we obtain an approximation to rn from the mean volume between the reference point and its nth neighbour and compare it with the heuristic and exact results.