THE 3-POINT CORRELATION-FUNCTION - MOMENT METHOD VS DIRECT COUNTING

For the study of clustering in small samples through correlation funct ions, the moment method is an efficient tool. In this paper we compare the direct counting with the moment method in the calculation of the spatial 3-point correlation function. The comparison is performed on a well known model of hierarchical clustering, the Soneira-Peebles mode l. The results given by both methods agree and the errors are of the s ame order. In the Appendix we supply some analytical expressions as we ll which are necessary in order to apply the moment method to the calc ulation of the 3-point correlation function.