Hello, We want to submit data to a hierarchical cluster analysis which weights each case by a value given for each case. In our case we are speaking of geographical entities which we would like to weight according to their population when clustering them according to a series of variables linked to this population. According to our ideas, the weighting should occur at two moments in the process: 1) in the calculation of the distance by multiplying (for each pair) the sum of squares by the product of the respective weights divided by the sum of the weights (if two pairs of observations are of equal euclidian distance, the pair with a higher weight should be considered of greater distance) 2) in the calculation of the ward criterion, by not using just the number of observations in each cluster, but a weighted sum of observations. However, skimming through the litterature I have not been able to find much references on weighting of cases (=observations). Much is said about weighting variables, but little about cases. Is this due to a simple lack of interest for such a procedure, or are there any mathematical/statistical reasons for not weighting cases ? If there is litterature on the topic which I have missed, could someone please point me to it ? Thank you, Moritz Lennert