In a variety of contexts, exogeny or exogeneity () is the fact of an action or object originating externally. It is the opposite of endogeneity or endogeny, the fact of being influenced from within a system.
Economics
In an
economics model, an
Exogenous change is one that comes from outside the model and is unexplained by the model. Such changes of an economic model from outside factors can include the influence of technology, in which this had previously been noted as an exogenous factor, but has rather been noted as a factor that can depict economic forces as a whole.
In economic sociology, Project IDEA (Interdisciplinary Dimensions of Economic Analysis) gave notion to understanding the exogenous factors that play a role within
economic theory. Developed from the International Social Science Council (ISSC) in the year of 1982, Project IDEA was founded to gather ideas from economists and sociologists in order to conceptualize what economic sociology incorporates, as they have sought to understand why these two fields have been estranged from each other.
Such exogenous factors in economic theory include laws placed in economic systems by governments, ranks of
in populations, and preferences based on social factors of an individual.
Exogenous factors in econometrics
In
econometrics, an endogenous
random variable is
correlation with the error term in the econometric model, while an exogenous variable is not.
However, exogenous variables aid in the explanation of endogenous variable variances. In the preset group, it is typical to include historical values of endogenous variables. Exogenous variables are independent of the model's
disturbance term, since they are preset. They meet the same conditions as explanatory variables do in a traditional
regression model.
Biology and medicine
Biology
An exogenous
contrast agent, in
medical imaging for example, is a liquid injected into the patient
intravenously that enhances visibility of a pathology, such as a
tumor. An exogenous factor is any material that is present and active in an individual
organism or living cell but that originated outside that organism, as opposed to an endogenous factor.
In the origins of , exogenous factors, namely those that are factors in inflammation or stress (such as overexertion, overeating, and extreme feelings of emotions of grief or anger), all contribute to exhaustion or modifications in .
DNA introduced to cells via transfection or viral transduction is an exogenous factor. Exogenous factors in DNA, particularly DNA damage, are more known as environmental factors that cause progression in the impairment of DNA.
Medicine and medical treatments
In
medicine, exogenous factors are seen in both
pathogens and
therapeutics. Exogenous factors can be included in the type of
obesity where there is an imbalance of food and
metabolism, in which one consumes a much greater amount than the human body can handle.
On the opposite end, endogenous obesity refers to obesity caused by disorders or issues outside an imbalance of food intake itself, which include
, interruption of
thyroid functions, and other syndromic disorders.
In relation to cancer, carcinogens are exogenous factors, in which these are made up of various factors (chemical, biological, physical), causing cancer after having entering through several routes of the body.
Social sciences
Philosophy
In
philosophy, the origins of existence of self, or the identity of self, emanating from, or sustaining, outside the natural or influenced realm, are exogenous.
Psychology
Exogenous constructivism prioritizes the reconstruction of structures that have already been created in the environment, which is based from a mechanical metaphor, and greatly reflects off of Bandura's social learning theory.
Overall, exogenous constructivism is noted to assume that knowledge comes from an individual's environment, which is assumed to be learned. Because an active individual is expected to be participating in the abstraction of knowledge from its environment, practical guidance of this result of participation remains the most crucial feature of directing the learning process. The structure of the individual's operating environment has a substantial impact on the structure of the knowledge generated.
Through the perspective of Piaget, learning was known as the individual's former structures accommodated to those imposed by its current environment. The individual's accommodation is directed by the environment, which provides the structures to which the individual must adapt.
In attentional psychology, exogenous stimuli are external stimuli without conscious intention.
Exogeny in other areas
Geography
In
geography, exogenous processes, unlike endogenic processes, originate from external forces acting on the
Earth and other planetary bodies, rather than from internal geological activity.
Weathering,
erosion, transportation and
sedimentation are the main exogenous processes. Asides from climate, exogenous geographic factors are able to contribute to the overall process of distribution, including densities of populations and
of certain areas in the world.
Exogeneity is proposed to ultimately cause geographic considerations to be rejected.
Ludology
In
ludology, the study of games, an exogenous item is anything outside the game itself. Therefore, an item in a massively multiplayer online game would have exogenous value if people were buying it with real world money rather than
in-game currency (though its in-game cost would be
endogenous). Noted as exogenous fantasy, one may also refer to this term as extrinsic stimuli or "fantasy"; these describe a
Fantasy game that solely relies on the skill being mastered, rather than the other way around.
These fantasies also tend to possess a few characteristics, such as (1) understanding that the fantasy and the skill that is being learned are inextricably linked, (2) the fantasy context and the instructional content being provided have an intrinsic and continuous link, and (3) endogenous fantasies tend to include more intellectually challenging and captivating content compared to exogenous fantasies.
Materials science
In materials science, an exogenous property of a substance is derived from outside or external influences, such as a nano-doped material.
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