Research Tips

Oversampling

Samples are often designed as simple random samples so that every member of a population (e.g., residents of a particular area, or customers of a particular company) has an equal chance of being selected. Sometimes, however, it’s better to give some members of the population a better chance than others of being selected. This is called oversampling and it’s typically done to ensure that there are a sufficient number of observations to complete all required analyses. Sometimes that is not possible with simple random sampling because it does not result in enough observations for members of particular subgroups (e.g., people of a particular age or income level), either because the subgroup makes up only a small proportion of the general population or because the response rate for the subgroup is lower than for the population as a whole.