Planned strategy based on the selection of a sample from a subpopulation (or more frequently from subpopulations) of a population on which the data are reported. The sampling is deliberately biased and is directed at the particular products or manufacturers. The subpopulations may or may not be determined on a risk basis. The specification of the ‘high - risk’ population comes from either scientific studies or previous analysis and information of other regions or countries. The sampling procedure can be random or not. The sampling from each subpopulation may not be proportional: the sample size is proportionally bigger for instance in subpopulations considered at high risk.