The deliberate selection of individuals of a rare type in order to obtain reasonably precise estimates of the properties of this type. In a population which includes such a rare type, a random sample of the entire population might result in very few (or none) of these individuals being selected. Oversampling implies the deliberate sampling of a much higher proportion of this type than of the rest of the population. This is a form of stratified sampling.
Subjects: Probability and Statistics — Sociology.