Quota sampling

Techniques > Research > Sampling > Quota sampling

Use | Method | Example | Discussion | See also

Use

Use when you know that the proportions of particular sub-groups within a population and you want to ensure each group is proportionately represented.

Method

Decide how many people you need to sample and then use whatever methods you can to access the desired sample size.

Example

A researcher in the high street wants 100 opinions about a new style of cheese. She sets up a stall and canvasses passers-by until she has got 100 people to taste the cheese and complete the questionnaire.

Discussion

There are several ways that a quota can be identified, including

Proportionate quota sampling: Balance across groups by population proportion.
Snowball sampling: Get sampled people to nominate others.

If care is not taken then significant bias can be introduced by quota sampling. In the example above, the people accessed may change with the time of day, the day of the week, whether they have an interest in cheese ang so on.

Quota sampling