Compound poisson approximations for the numbers of extreme spacings

The accuracy of the Poisson approximation to the distribution of the numbers of large and small m-spacings, when n points are placed at random on the circle, was analysed using the Stein.Chen method in Barbour et al. (1992b). The Poisson approximation for m.2 was found not to be as good as for 1-spacings. In this paper, rates of approximation of these distributions to suitable compound Poisson distributions are worked out, using the CP.Stein.Chen method and an appropriate coupling argument. The rates are better than for Poisson approximation for m.2, and are of order O((log n)2/n) for large m-spacings and of order O(1/n) for small m-spacings, for any fixed m.2, if the expected number of spacings is held constant as n . ..