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  2. Selection bias - Wikipedia

    en.wikipedia.org/wiki/Selection_bias

    Selection bias. Selection bias is the bias introduced by the selection of individuals, groups, or data for analysis in such a way that proper randomization is not achieved, thereby failing to ensure that the sample obtained is representative of the population intended to be analyzed. [1] It is sometimes referred to as the selection effect.

  3. Sampling (statistics) - Wikipedia

    en.wikipedia.org/wiki/Sampling_(statistics)

    Sampling (statistics) In statistics, quality assurance, and survey methodology, sampling is the selection of a subset or a statistical sample (termed sample for short) of individuals from within a statistical population to estimate characteristics of the whole population. The subset is meant to reflect the whole population and statisticians ...

  4. Self-selection bias - Wikipedia

    en.wikipedia.org/wiki/Self-selection_bias

    Self-selection bias. In statistics, self-selection bias arises in any situation in which individuals select themselves into a group, causing a biased sample with nonprobability sampling. It is commonly used to describe situations where the characteristics of the people which cause them to select themselves in the group create abnormal or ...

  5. Heckman correction - Wikipedia

    en.wikipedia.org/wiki/Heckman_correction

    Heckman correction. The Heckman correction is a statistical technique to correct bias from non-randomly selected samples or otherwise incidentally truncated dependent variables, a pervasive issue in quantitative social sciences when using observational data. [1] Conceptually, this is achieved by explicitly modelling the individual sampling ...

  6. Nonprobability sampling - Wikipedia

    en.wikipedia.org/wiki/Nonprobability_sampling

    Such samples are biased because they give people with more social connections an unknown but higher chance of selection, [10] but lead to higher response rates. Judgment sampling or purposive sampling, where the researcher chooses the sample based on who they think would be appropriate for the study. This is used primarily when there is a ...

  7. Survey sampling - Wikipedia

    en.wikipedia.org/wiki/Survey_sampling

    In statistics, survey sampling describes the process of selecting a sample of elements from a target population to conduct a survey. The term "survey" may refer to many different types or techniques of observation. In survey sampling it most often involves a questionnaire used to measure the characteristics and/or attitudes of people.

  8. Sampling bias - Wikipedia

    en.wikipedia.org/wiki/Sampling_bias

    In statistics, sampling bias is a bias in which a sample is collected in such a way that some members of the intended population have a lower or higher sampling probability than others. It results in a biased sample[1] of a population (or non-human factors) in which all individuals, or instances, were not equally likely to have been selected. [2]

  9. Snowball sampling - Wikipedia

    en.wikipedia.org/wiki/Snowball_sampling

    Snowball sampling. In sociology and statistics research, snowball sampling[1] (or chain sampling, chain-referral sampling, referral sampling[2][3]) is a nonprobability sampling technique where existing study subjects recruit future subjects from among their acquaintances. Thus the sample group is said to grow like a rolling snowball.