Purposive sampling

Techniques > Research > Sampling > Purposive sampling

Use | Method | Example | Discussion | See also

Use

Use when you want to access a particular subset of people.

Method

When taking the sample, reject people who do not fit a particular profile.

Example

A researcher wants to get opinions from non-working mothers. They go around an area knocking on doors during the day when children are likely to be at school. They ask to speak to the 'woman of the house. Their first questions are then about whether there are children and whether the woman has a day job.

Discussion

Purposive sampling starts with a purpose in mind and the sample is thus selected to include people of interest and exclude those who do not suit the purpose.

This method is popular with newspapers and magazines which want to make a particular point. This is also true for marketing researchers who are seeking support for their product. They typically start with people in the street, first approaching only 'likely suspects' and then starting with questions that reject people who do not suit.

Purposive sampling is non-probability and hence can be subject to bias and error.