Selection Bias

A Selection Bias is a bias that results in biased samples.

• Context:
  • It can (often) stem from an absence of comparability between groups being studied.
• See: Biased Dataset, Survival Bias, Logical Error, Sampling, Internal Experiment Validity.

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References

2021

• (Wikipedia, 2021) ⇒ https://en.wikipedia.org/wiki/selection_bias Retrieved:2021-5-19.
  • 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 ensuring that the sample obtained is not representative of the population intended to be analyzed. It is sometimes referred to as the selection effect. The phrase "selection bias" most often refers to the distortion of a statistical analysis, resulting from the method of collecting samples. If the selection bias is not taken into account, then some conclusions of the study may be false.

2002

• (Grimes & Schulz, 2002) ⇒ David A Grimes, and Kenneth F Schulz. (2002). “Bias and Causal Associations in Observational Research." The Lancet, The Lancet, 359(9302). doi:10.1016/S0140-6736(02)07451-2
  • QUOTE: Readers of medical literature need to consider two types of validity, internal and external. Internal validity means that the study measured what it set out to; external validity is the ability to generalise from the study to the reader's patients. With respect to internal validity, selection bias, information bias, and confounding are present to some degree in all observational research. Selection bias stems from an absence of comparability between groups being studied.

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