Biases

Here is a list of all Biases in the Catalogue.  Check back regularly as we are adding new ones over time.

 

Adherence bias

A systematic distortion in outcome data that arises when participants who adhere to a study protocol or intervention differ from those who do not adhere, when that difference relates to the outcome of interest.

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Admission rate bias

Arises when the variables under study are affected by the selection of hospitalized subjects leading to a bias between the exposure and the disease under study.

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Allocation bias

Systematic difference in how participants are assigned to comparison groups in a clinical trial.

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Ascertainment bias

Systematic differences in the identification of individuals included in a study or distortion in the collection of data in a study.

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Availability bias

A distortion that arises from the use of information which is most readily available, rather than that which is necessarily most representative.

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Centripetal bias

The reputations of certain clinicians and institutions cause individuals with specific disorders or exposures to gravitate toward them.

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Chronological bias

When study participants allocated earlier to an intervention or a group are subject to different exposures or are at a different risk from participants who are recruited later.

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Collider bias

A distortion that modifies an association between an exposure and outcome, caused by attempts to control for a common effect of the exposure and outcome

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Compliance bias

Participants compliant with an intervention differ in some way from those not compliant which can systematically affect the outcome of interest.

[NOTE: as of 18 July 2023 this bias has been superseded by Adherence bias. A detailed explanation is given here]

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Confounding

A distortion that modifies an association between an exposure and an outcome because a factor is independently associated with the exposure and the outcome.

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