Self-selection
Encyclopedia
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 undesirable conditions in the group.
Self-selection bias is a major problem in research in sociology
, psychology
, economics
and many other social sciences
. In such fields, a poll suffering from such bias is termed a self-selecting opinion poll or "SLOP".
The term is also used in criminology
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
, 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.
. For example, one might note significantly higher test scores among those who participate in a test preparation course, and credit the course for the difference. However, due to self-selection, there are a number of differences between the people who chose to take the course and those who chose not to. Those who chose to take the course might have been more hard-working, studious, and dedicated than those who did not, and that difference in dedication may have affected the test scores between the two groups. If that was the case, then it is not meaningful to simply compare the two sets of scores. Due to self-selection, there were other factors affecting the scores than merely the course itself.
Self-selection bias causes problems for research about programs or products. In particular, self-selection makes it difficult to evaluate
programs, to determine whether the program has some effect, and makes it difficult to do market research
.
Self-selection bias at the Skeptic's Dictionary
Statistics
Statistics is the study of the collection, organization, analysis, and interpretation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments....
, self-selection bias arises in any situation in which individuals select themselves into a group
Group (sociology)
In the social sciences a social group can be defined as two or more humans who interact with one another, share similar characteristics and collectively have a sense of unity...
, causing a biased sample
Biased sample
In statistics, sampling bias is when a sample is collected in such a way that some members of the intended population are less likely to be included than others. It results in a biased sample, a non-random sample of a population in which all individuals, or instances, were not equally likely to...
with nonprobability sampling
Nonprobability sampling
Sampling is the use of a subset of the population to represent the whole population. Probability sampling, or random sampling, is a sampling technique in which the probability of getting any particular sample may be calculated. Nonprobability sampling does not meet this criterion and should be...
. 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.
Self-selection bias is a major problem in research in sociology
Sociology
Sociology is the study of society. It is a social science—a term with which it is sometimes synonymous—which uses various methods of empirical investigation and critical analysis to develop a body of knowledge about human social activity...
, psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
, economics
Economics
Economics is the social science that analyzes the production, distribution, and consumption of goods and services. The term economics comes from the Ancient Greek from + , hence "rules of the house"...
and many other social sciences
Social sciences
Social science is the field of study concerned with society. "Social science" is commonly used as an umbrella term to refer to a plurality of fields outside of the natural sciences usually exclusive of the administrative or managerial sciences...
. In such fields, a poll suffering from such bias is termed a self-selecting opinion poll or "SLOP".
The term is also used in criminology
Criminology
Criminology is the scientific study of the nature, extent, causes, and control of criminal behavior in both the individual and in society...
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
Selection bias is a statistical bias in which there is an error in choosing the individuals or groups to take part in a scientific study. It is sometimes referred to as the selection effect. The term "selection bias" most often refers to the distortion of a statistical analysis, resulting from the...
, 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 it difficult to determine causationCausation
Causation may refer to:* Causation , a key component to establish liability in both criminal and civil law* Causation in English law defines the requirement for liability in negligence...
. For example, one might note significantly higher test scores among those who participate in a test preparation course, and credit the course for the difference. However, due to self-selection, there are a number of differences between the people who chose to take the course and those who chose not to. Those who chose to take the course might have been more hard-working, studious, and dedicated than those who did not, and that difference in dedication may have affected the test scores between the two groups. If that was the case, then it is not meaningful to simply compare the two sets of scores. Due to self-selection, there were other factors affecting the scores than merely the course itself.
Self-selection bias causes problems for research about programs or products. In particular, self-selection makes it difficult to evaluate
Program evaluation
Project evaluation is a systematic method for collecting, analyzing, and using information to answer questions about projects, policies and programs, particularly about their effectiveness and efficiency...
programs, to determine whether the program has some effect, and makes it difficult to do market research
Market research
Market research is any organized effort to gather information about markets or customers. It is a very important component of business strategy...
.
External links
Self-selection bias at MoneytermsSelf-selection bias at the Skeptic's Dictionary