On the estimation of the spherical contact distribution Hs(y) for spatial point processes

RIPLEY (1977, Journal of the Royal Statistical Society, B39 172-212) proposed an estimator for the spherical contact distribution Hs(s), of a spatial point process observed in a bounded planar region. However, this estimator is not defined for some distances of interest, in this bounded region. A new estimator for Hs(y), is proposed for use with regular grid of sampling locations. This new estimator is defined for all distances of interest. It also appears to have a smaller bias and a smaller mean squared error than the previously suggested alternative. (author). 11 refs, 4 figs, 1 tab