Sampling bias

"Spotlight fallacy" redirects here. For the psychological effect, see Spotlight effect.
A pie chart showing the results of a hypothetical survey, in which the question asked was "Do you enjoy responding to surveys?" The chart shows that 99.8 percent of participants said, "Yes, I love responding to surveys!" and that 0.2 percent said "No, I throw them in the trash"
An example of a biased sample in a hypothetical population survey, which asks if participants like responding to surveys, thus selecting for the individuals who were most likely to respond in the first place.

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] If this is not accounted for, results can be erroneously attributed to the phenomenon under study rather than to the method of sampling.

Medical sources sometimes refer to sampling bias as ascertainment bias.[3][4] Ascertainment bias has basically the same definition,[5][6] but is still sometimes classified as a separate type of bias.[5]

  1. ^ "Sampling Bias". Medical Dictionary. Archived from the original on 10 March 2016. Retrieved 23 September 2009.
  2. ^ "Biased sample". TheFreeDictionary. Retrieved 23 September 2009. Mosby's Medical Dictionary, 8th edition
  3. ^ Weising K (2005). DNA fingerprinting in plants: principles, methods, and applications. London: Taylor & Francis Group. p. 180. ISBN 978-0-8493-1488-9.
  4. ^ Ramírez i Soriano A (29 November 2008). Selection and linkage desequilibrium tests under complex demographies and ascertainment bias (PDF) (Ph.D. thesis). Universitat Pompeu Fabra. p. 34.
  5. ^ a b Panacek EA (May 2009). "Error and Bias in Clinical Research" (PDF). SAEM Annual Meeting. New Orleans, LA: Society for Academic Emergency Medicine. Archived from the original (PDF) on 17 August 2016. Retrieved 14 November 2009.
  6. ^ "Ascertainment Bias". Medilexicon Medical Dictionary. Archived from the original on 6 August 2016. Retrieved 14 November 2009.