Non-probability sampling (market research)

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Non-probability sampling (market research)

Non-probability sampling is not generally encouraged in market research as it is not possible to apply findings from this kind of sample to the wider population.

That said, when the project in question is small scale, particularly if it is qualitative in nature, it may be acceptable to utilise non-probability sample, for instance if you were seeking to understand complex sociological issues and needed to speak to a small number of experts.

There are several types of non-probability sampling, including:

  • Convenience sampling: The sampling of friends, relatives, co-workers or people shopping in a particular store etc. This is called convenience because the respondents are 'close to hand', but is biased due to the fact the researchers or recruiters may subconsciously approach some people and avoid approaching others.
  • Snowballing or snowball sampling: Sample is acquired by asking each respondent to recruit a friend. This is biased as it gives people with more social connections an unknown but increased chance of being selected.
  • Judgemental/purposive sampling: The researcher selects who they think would be best to be involved in the research study. Most often used when there are a limited number of people with relevant knowledge or experience of the subject matter.

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