Biases

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

 

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 treatment and 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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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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Compliance bias

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

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Confirmation bias

is the search for and use of information to support an individual’s ideas, beliefs or hypotheses.

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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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Confounding by indication

A distortion that modifies an association between an exposure and an outcome, caused by the presence of an indication for the exposure that is the true cause of the outcome.

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Diagnostic access bias

Individuals differ in their geographic, temporal and economic access to diagnostic procedures which label them as having a given disease.

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Diagnostic suspicion bias

Knowledge of a subject’s prior exposures or personal biases may influence both the process and the outcome of diagnostic tests.

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Hawthorne effect

When individuals modify an aspect of their behaviour in response to their awareness of being observed.

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