What is Selection Bias?
Error due to non-random selection of study participants; leads to unrepresentative sample.
Selection bias can significantly affect the validity of study results by skewing the sample population.
What is Berkson’s Bias?
Type of selection bias; hospital-based patients may differ systematically from general population.
Berkson’s bias often arises in studies using hospital patients, affecting generalizability.
What is Neyman’s Bias (Prevalence-Incidence Bias)?
Cases with severe or short-duration disease are missed, leading to underestimation.
This bias can occur in cross-sectional studies where only prevalent cases are examined.
What is Attrition Bias?
Bias from loss to follow-up, especially if loss is related to exposure/disease.
Attrition bias can result in an incomplete dataset, affecting the study’s conclusions.
What is Information Bias?
Systematic error in measuring exposure or outcome.
Information bias can arise from misclassification of participants or inaccurate data collection.
What is Recall Bias?
Patients with disease remember exposures more clearly than those without disease. Common in case-control studies.
Recall bias can lead to overestimation of the association between exposure and outcome.
What is Observer Bias?
Researcher’s prior knowledge influences how data is recorded/interpreted.
Observer bias can compromise the objectivity of data collection and analysis.
What is Reporting Bias?
Subjects underreport or overreport certain exposures (e.g., alcohol use, smoking).
Reporting bias can significantly distort the true relationship between exposure and outcome.
What is Surveillance Bias (Detection Bias)?
Disease more likely diagnosed in those under closer medical surveillance.
This bias can lead to an apparent increase in incidence rates among certain populations.
What is Lead-time Bias?
Early detection appears to prolong survival, but actual disease course unchanged.
Lead-time bias is often a concern in cancer screening studies.
What is Length-time Bias?
Screening detects more slowly progressing diseases, making survival look better.
Length-time bias can give a false impression of a treatment’s effectiveness.
What is Confounding Bias?
Third variable distorts the true association between exposure and outcome.
Confounding bias can be controlled through study design or statistical methods.
What is Publication Bias?
Positive findings more likely to be published than negative/null studies.
Publication bias can skew the literature and lead to an overestimation of treatment effects.
