Online Market Research

Quota sampling is frequently used in survey designs, and especially in market research projects.  This technique is a form of "convenience sampling," where respondents are chosen not at random, but because they are available or easier to reach.  A probability-based sampling design is not employed, due to decisions made by the researcher based upon various reasons: the population frame cannot be known, contact information for respondents is unavailable, or even because the time, effort and costs are simply too high for the budget.

Quota sampling is a way that you can gather completed questionnaires, producing adequate amounts of data, from people with different demographic attributes.  Often, market researchers want to ensure they get roughly equal amounts of data from males and females, may be interested only in a specific age range (i.e., their target market/demographic), or would like to know if preferences differ by other characteristics such as ethnicity and income level.

So where does the “quota” come into play?  Well, just as in stratified sampling, the population is divided into mutually exclusive subgroubs, often based on demographic characteristics.  The researcher sets a quota for each subgroup (100 females and 100 males, for example), collects data until the quotas are met, then stops data collection and begins data analysis.  The reason that quota sampling is not a probability-based sampling technique, thereby limiting your ability to generalize, is because respondents are not selected at random.  Quota sampling does go a step further than simply selecting whomever is available without regard to any criteria, and that's why it is used so often.