Statistics Dictionary

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Non-Probability Sampling

Statisticians distinguish between two broad categories of sampling .

  • Probability sampling. With probability sampling, every element of the population has a known probability of being included in the sample.

  • Non-probability sampling. With non-probability sampling, we cannot specify the probability that each element will be included in the sample.

The main advantages of non-probability sampling are convenience and cost. However, with non-probability samples, we cannot make probability statements about our sample statistics. For example, we cannot compute a confidence interval for an estimation problem or a region of acceptance for a hypothesis test. Probability samples are required to compute those measures.

See also:   Tutorial: Survey Sampling