Table 1

Alphabetical list of biases, indicating their type and the design where they can occur

Specific name of bias	Group of bias	Subgroup of bias (next level to specific name)	Type of design affected
Allocation of intervention bias	Execution of an intervention		Trial
Apprehension bias	Information bias	Observer bias	All studies
Ascertainment bias	Selection bias	Inappropriate definition of the eligible population	Observational study
Berkson’s bias	Selection bias	Inappropriate definition of the eligible population	Hospital based case-control study
Centripetal bias	Selection bias	Healthcare access bias	Observational study
Citation bias	Selection bias	Lack of accuracy of sampling frame	Systematic review/meta-analysis
Competing risks	Selection bias	Ascertainment bias	All studies
Compliance bias	Execution of an intervention		Trial
Confounding by group	Confounding		Ecological study
Confounding by indication	Confounding		Case-control study, cohort study
Contamination bias	Execution of an intervention		Trial, mainly community trials
Detection bias	Selection bias	Uneven diagnostic procedures in the target population	Case-control study
Detection bias	Information bias	Misclassification bias	Cohort study
Diagnostic/treatment access bias	Selection bias	Healthcare access bias	Observational study
Diagnostic suspicion bias	Selection bias	Detection bias	Case-control study
Diagnostic suspicion bias	Information bias	Detection bias	Cohort study
Differential maturing			Trial
Differential misclassification bias	Information bias	Misclassification bias	All studies
Dissemination bias	Selection bias	Lack of accuracy of sampling frame	Systematic review/meta-analysis
Ecological fallacy	Information bias		Ecological study
Exclusion bias	Selection bias	Inappropriate definition of the eligible population	Case-control study
Exposure suspicion bias	Information bias	Recall bias	Case-control study
Family aggregation bias	Information bias	Reporting bias	Observational study
Friend control bias	Selection bias	Inappropriate definition of the eligible population	Case-control study
Hawthorne effect	Information bias		Trial
Healthcare access bias	Selection bias	Ascertainment bias	Observational study
Healthy volunteer bias	Selection bias	Non-response bias	Observational study
Healthy worker effect	Selection bias	Inappropriate definition of the eligible population	Cohort study (mainly retrospective)
Incidence-prevalence bias (synonym of Neyman bias)
Inclusion bias	Selection bias	Inappropriate definition of the eligible population	Hospital based case-control study
Lack of intention to treat analysis			Randomised trial
Language bias	Selection bias	Inappropriate definition of the eligible population	Systematic review/meta-analysis
Lead-time bias	Information bias		Screening study
Length biased sampling	Selection bias	Ascertainment bias	Cross sectional study, screening
Losses/withdrawals to follow up	Selection bias	During study implementation	Cohort study, trial
Mimicry bias	Selection bias	Detection bias	Case-control study
Mimicry bias	Information bias	Detection bias	Cohort study
Misclassification bias	Information bias		All studies
Missing information in multivariable analysis	Selection bias	During study implementation	All studies (mainly retrospective)
Mode for mean bias	Information bias	Reporting bias	All studies
Neyman bias	Selection bias	Ascertainment bias	Cross sectional study, case-control study with prevalent cases
Non-differential misclassification bias	Information bias	Misclassification bias	All studies
Non-random sampling bias	Selection bias	Lack of accuracy of sampling frame	Observational study
Non-response bias	Selection bias	During study implementation	Observational study
Obsequiousness bias	Information bias	Reporting bias	All studies
Observer expectation bias	Information bias	Observer bias	All studies
Observer/interviewer bias	Information bias	Misclassification bias	All studies
Overmatching	Selection bias	Inappropriate definition of the eligible population	Case-control study
Participant expectation bias	Information bias	Recall bias	Trial
Popularity bias	Selection bias	Healthcare access bias	Observational study
Post hoc analysis	Selection bias	Publication bias	Systematic review/meta-analysis
Protopathic bias	Information bias		Observational study
Publication bias	Selection bias	Lack of accuracy of sampling frame	Systematic review/meta-analysis
Purity diagnostic bias	Selection bias	Spectrum bias	Validity of diagnostic tests
Recall bias	Information bias	Misclassification bias	All studies
Referral filter bias	Selection bias	Healthcare access bias	Observational study
Regression dilution bias	Information bias	Regression to the mean	Cohort study, trial
Regression to the mean	Information bias		Cohort study, trial
Relative control bias	Selection bias	Inappropriate definition of the eligible population	Case-control study
Reporting bias	Information bias	Misclassification bias	All studies
Rumination bias	Information bias	Recall bias	Case-control study, retrospective cohort study
Selective survival bias (synonym of Neyman bias)
Sick quitter bias	Information bias	Protopathic bias	Observational study
Spectrum bias	Selection bias	Ascertainment bias	Validity of diagnostic tests (mainly case-control study)
Survivor treatment selection bias	Selection bias	Ascertainment bias	Cohort study (mainly retrospective)
Susceptibility bias (synonym of confounding)
Telephone random sampling bias	Selection bias	Non-random sampling bias	Observational study
Temporal ambiguity	Information bias		Cross sectional study, ecological study
Unacceptable disease/exposure	Information bias	Reporting bias	Observational study
Underreporting bias	Information bias	Reporting bias	Observational study
Unmasking—detection signal—bias	Selection bias	Detection bias	Case-control study
Verification bias (synonym of work up bias)
Will Rogers phenomenon	Information bias		Prognostic (mainly cohort) study
Work up bias	Information bias		Validity of diagnostic test (retrospective study)