Sampling (statistics)

In probability theory and statistics, sampling refers to the selection of individuals from a population of interest (or the collection of data on those individuals).

Methods of statistical sampling include:

• simple random sampling
• systematic sampling[?]
• stratified sampling
• cluster sampling
• multistage sampling

These are all examples of probability sampling[?], or random sampling[?], in which the probability of getting any particular sample[?] may be calculated based on a probability model[?]. A sampling method that does not meet this criterion is called nonprobability sampling[?].

An example of nonprobability sampling[?] is convenience sampling[?], in which members of the population are chosen based on their relative ease of access.