In saturated markets the need of segmentation is increasing. By the method of cluster analysis all members of a panel are separated in relevant segments for this product category. The efficiency and validity of the segmentation is proved by comparing the buying behaviour between the different clusters in terms of number of buyers, quantity bought, product-types, brands etc. Because media exposure is known from all panel members this can very easy be analysed for each cluster. The success of marketing activities of the manufacturer focussed on an special cluster in the population can later on be controlled by looking for changes of the purchasing habits of the panel members is that cluster. A practical application of this type of segmentation in the G&I household-panel is shown for a food product field.