statistics Statistics (from German language, German: ', "description of a State (polity), state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a s ...

, self-selection bias arises in any situation in which individuals select themselves into a

group A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...

, causing a biased sample with

nonprobability sampling Nonprobability sampling is a form of Sampling (statistics), sampling that does not utilise random sampling techniques where the probability of getting any particular sample may be calculated. Nonprobability samples are not intended to be used to ...

. 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 undesirable conditions in the group. It is closely related to the non-response bias, describing when the group of people responding has different responses than the group of people not responding. Self-selection bias is a major problem in research in

sociology Sociology is the scientific study of human society that focuses on society, human social behavior, patterns of Interpersonal ties, social relationships, social interaction, and aspects of culture associated with everyday life. The term sociol ...

psychology Psychology is the scientific study of mind and behavior. Its subject matter includes the behavior of humans and nonhumans, both consciousness, conscious and Unconscious mind, unconscious phenomena, and mental processes such as thoughts, feel ...

economics Economics () is a behavioral science that studies the Production (economics), production, distribution (economics), distribution, and Consumption (economics), consumption of goods and services. Economics focuses on the behaviour and interac ...

and many other

social sciences Social science (often rendered in the plural as the social sciences) is one of the branches of science, devoted to the study of society, societies and the Social relation, relationships among members within those societies. The term was former ...

. In such fields, a poll suffering from such bias is termed a self-selected listener opinion poll or "SLOP". The term is also used in

criminology Criminology (from Latin , 'accusation', and Ancient Greek , ''-logia'', from λόγος ''logos'', 'word, reason') is the interdisciplinary study of crime and deviant behaviour. Criminology is a multidisciplinary field in both the behaviou ...

to describe the process by which specific predispositions may lead an offender to choose a criminal career and lifestyle. While the effects of self-selection bias are closely related to those of

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 inte ...

, the problem arises for rather different reasons; thus 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.

Explanation

Self-selection makes determination of causation more difficult. For example, when attempting to assess the effect of a test preparation course in increasing participant's test scores, significantly higher test scores might be observed among students who choose to participate in the preparation course itself. Due to self-selection, there may be a number of differences between the people who choose to take the course and those who choose not to, such as motivation, socioeconomic status, or prior test-taking experience. Due to self-selection according to such factors, a significant difference in mean test scores could be observed between the two populations independent of any ability of the course to affect test scores. An outcome might be that those who elect to do the preparation course would have achieved higher scores in the actual test anyway. If the study measures an improvement in absolute test scores due to participation in the preparation course, they may be skewed to show a higher effect. A relative measure of 'improvement' might improve the reliability of the study somewhat, but only partially. Self-selection bias causes problems for research about programs or products. In particular, self-selection affects

evaluation In common usage, evaluation is a systematic determination and assessment of a subject's merit, worth and significance, using criteria governed by a set of Standardization, standards. It can assist an organization, program, design, project or any o ...

of whether or not a given program has some effect, and complicates interpretation of

market research Market research is an organized effort to gather information about target markets and customers. It involves understanding who they are and what they need. It is an important component of business strategy and a major factor in maintaining com ...

. The

Roy model The Roy model is one of the earliest works in economics on self-selection due to A. D. Roy. The basic model considers two types of workers that choose occupation in one of two sectors. Original model Roy's original paper deals with workers select ...

provides one of the earliest academic illustrations of the self-selection problem.

References

* Jacobs, B., Hartog, J., Vijverberg, W. (2009) "Self-selection bias in estimated wage premiums for earnings risk", ''Empirical Economics'', 37 (2), 271–286.

External links

Self-selection bias
at Moneyterms

at the Skeptic's Dictionary {{DEFAULTSORT:Self-Selection bias Design of experiments Sampling (statistics) Bias

Explanation

See also

References

External links