Dear R-list. I would need to know if the centroid of a cluster, whose coordinates are the average of the coordinates of the points in the cluster, is also the point that minimizes the sum of its distances from all the points in the cluster. If so, where could I find a proof? Since I understand this question is not directly connected to R, I would greatly appreciate if someone could just point me to a more appropriate mailing list. Thank you, Bruno ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Bruno L. Giordano, Ph.D. CIRMMT Schulich School of Music, McGill University 555 Sherbrooke Street West Montr?al, QC H3A 1E3 Canada http://www.music.mcgill.ca/~bruno/