Self-Selection Bias

Examples of Self-Selection Bias in the following topics:

• The Problems with Polls

  • Problems with polls typically stem either from issues with the methodology that bias the sample or the responses that cause the bias.
  • Because of this selection bias, the characteristics of those who agree to be interviewed may be markedly different from those who decline.
  • Selection bias occurs when some units have a differing probability of selection that is unaccounted for by the researcher.
  • In statistics, self-selection bias arises in any situation in which individuals select themselves into a group, causing a biased sample with non-probability sampling.
  • There may be a purposeful intent on the part of respondents leading to self-selection bias whereas other types of selection bias may arise more inadvertently, possibly as the result of mistakes by those designing any given study.

• Constructing Public Opinion Surveys

  • Self-selection bias: Although the individuals chosen to participate in surveys are often randomly sampled, errors due to non-responses may exist.

• Media Bias

  • Media bias is the bias of journalists and news producers in the selection of events and stories that are reported, and how they are covered.
  • Media bias is the bias of journalists and news producers within the mass media, concerning the selection of events and stories that are reported, and how they are covered.
  • Because it is impossible to report everything, selectivity is inevitable.
  • The most commonly discussed forms of bias occur when the media support or attack a particular political party, candidate, or ideology; however, other common forms of bias exist, including advertising bias, corporate bias, mainstream bias, sensationalism, and concision bias.
  • Advertising bias refers to when stories are selected or slanted to please advertisers; corporate bias refers to when stories are selected or slanted to please corporate owners of media; mainstream bias refers to a tendency to report what everyone else is reporting, and to avoid stories that will offend anyone.

• Conducting Polls

  • Steps to conduct a poll effectively including identifying a sample, evaluating poll questions, and selecting a question and response mode.
  • Prior previous questions may bias later questions.
  • Finally, questionnaires can be administered by research staff, by volunteers or self-administered by the respondents.

• The Rise of Adversarial Journalism

  • This type of journalism is always premeditated and used to defame or discredit interviewees by portraying them as self-contradictory, malevolent, unqualified, or immoral.
  • This effect is also achieved by replaying selected quotes from public speeches, followed by hand-picked footage or images that appear to reinforce negative images of the interviewee.
  • Public figures could no longer sue for libel, regardless of the bias of news media, without proof that the media had acted maliciously.

• Sampling Techniques

  • Each element has an equal probability of selection.
  • Furthermore, any given pair of elements has the same chance of selection as any other pair.
  • This minimizes bias and simplifies analysis of results.
  • Sometimes it is more cost-effective to select respondents in groups ("clusters").
  • In quota sampling the selection of the sample is non-random.

• Models of Political Socialization

  • Psychological theories of self development have been broadened by sociologists who explicitly study the role of society and social interaction in self development.
  • Charles Cooley and George Mead both contributed significantly to the sociological understanding of the development of self.
  • By this stage of development, an individual is able to imagine how he or she is viewed by one or many others—and thus, from a sociological perspective, to have a "self" (Mead 1934; Mead 1964).
  • Another sociologist, Carol Gilligan (1936–), recognized that Kohlberg's theory might show gender bias since his research was only conducted on male subjects.

• Telephone and Internet Polling

  • Due to the lack of sampling frames, many online survey invitations are published in the form of an URL link on web sites or in other media, which leads to sample selection bias that is out of research control and to non-probability samples.
  • For instance, there is some potential for interviewer bias (e.g. some people may be more willing to discuss a sensitive issue with a female interviewer than with a male one), telephone polling cannot be used for non-audio information (graphics, demonstrations, taste/smell samples), and it is unreliable for consumer surveys in rural areas where telephone density is low .

• Winning an Election: Majority, Plurality, and Proportional Representation

  • Majority rule is a decision rule that selects the option which has a majority, that is, more than half the votes.
  • Proportional representation is an alternative to voting systems based on single member districts or on bloc voting; these non-PR systems tend to produce disproportionate outcomes and to have a bias in favor of larger political groups.

• The Sixth Amendment and Jury Trials

  • At voir dire, each side may question potential jurors to determine any bias, and challenge them if the same is found; the court determines the validity of these challenges for cause.
  • Another factor in determining the impartiality of the jury is the nature of the panel from which the jurors are selected.
  • The jury panel must represent a fair cross-section of the community; the defendant may establish that the requirement was violated by showing that the allegedly excluded group is a "distinctive" one in the community, that the representation of such a group in venires is unreasonable and unfair in regard to the number of persons belonging to such a group, and that the under-representation is caused by a systematic exclusion in the selection process.