Biases

Adherence bias

A 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.

A distortion in assessment of the relation between an exposure and a disease that the exposure is thought to affect, which arises because the subjects studied had been admitted to hospital, typically increasing the odds ratio but in some cases reducing it. Also known as Berkson’s bias.

All’s well literature bias

A distortion in favour of a dominant theory or hypothesis by ignoring or downplaying alternative theories or hypotheses.

Allocation bias

A distortion in the size of an outcome in a clinical trial, due to a systematic difference in how participants are allocated to comparison groups.

Apprehension bias

A distortion in the size of a measurement or outcome in a clinical study, when a study participant responds differently to an intervention, because they are worried or concerned about being observed.

Ascertainment bias

A distortion in data, as presented or analysed, that have been collected in such a way that some members of the target population are more or less likely to be included in the final results than others, creating a difference between the study population and the target population.

Attrition bias

A distortion in outcomes in a clinical trial when there are unequal losses of participants from different study groups.

Availability bias

A distortion in anything that relies on interpretation of evidence, arising from the use of information which is most readily available, rather than that which is necessarily most representative.

Biases of rhetoric

An argument used to persuade the reader without appealing to reason or evidence.

Centripetal bias

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

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.

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

Compliance bias

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

Confirmation bias

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

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.

Catalogue of Bias

Adherence bias

Admission rate bias

All’s well literature bias

Allocation bias

Apprehension bias

Ascertainment bias

Attrition bias

Availability bias

Biases of rhetoric

Centripetal bias

Chronological bias

Collider bias

Compliance bias

Confirmation bias

Confounding