Part Three Disease Detectives (Study Types, Design, Bias)

What is the focus of ecological studies?

Focus on groups rather than individuals, analyzing populations that share common characteristics.

What is a key limitation of ecological studies?

Can only establish correlation, not causation, and are prone to ecological fallacy.

What do cross-sectional studies assess?

assess the prevalence of a condition or characteristic in a population at a single point in time.

What is a major disadvantage of cross-sectional studies?

They cannot establish causation and are susceptible to recall bias.

What is the purpose of case-control studies?

Studies that compare individuals with a specific disease (cases) to those without it (controls) to identify differences in exposure or risk factors.

What is a primary advantage of cohort studies?

Can establish temporal relationships between exposure and outcome.

What is a disadvantage of cohort studies?

are expensive and time-consuming, especially when conducted prospectively.

What distinguishes randomized controlled trials (RCTs) from other study designs?

Involve random assignment of participants to intervention or control groups, minimizing bias and establishing causation.

What are quasi-experiments?

Resemble RCTs but lack random assignment, often used when randomization is not feasible.

What is morbidity?

Refers to the rate of disease in a population.

What is mortality?

Refers to the rate of death in a population.

What is recall bias?

The inaccurate memory of exposure or symptoms, particularly in retrospective studies.

What is selection bias?

Refers to systematic differences between those selected for study and those not, affecting generalizability.

What is confounding in research?

When a third variable distorts the relationship between exposure and outcome.

What is observer bias?

When a researcher's expectations influence data collection or interpretation.

What is reporting bias?

Occurs when participants selectively reveal or withhold information, often about stigmatized behaviors.

What is survivorship bias?

Happens when only those who survived a condition are studied, excluding fatal cases.

What is misclassification bias?

Occurs when subjects are incorrectly placed in the wrong group, such as exposure or outcome misrecorded.

What is nonresponse bias?

Arises when people who do not participate differ significantly from those who do.

What is detection bias?

Occurs when differences in diagnostic practices affect detection rates between groups.

What is publication bias?

When only positive or significant findings are published or known.

What is interviewer bias?

Occurs when the way a question is asked influences the respondent's answer.

What is recall decay?

Refers to the fading of memory over time, affecting data accuracy in long-term studies.

What is the healthy worker effect?

employed populations tend to be healthier than the general population, skewing occupational studies.

What is lead-time bias?

occurs when early detection appears to increase survival time, even if prognosis remains unchanged.

What is length-time bias?

happens when screening is more likely to detect slower-progressing cases, inflating survival estimates.

What is attrition bias?

refers to the loss of participants over time, distorting results, especially in cohort studies.

What is channeling bias?

occurs when certain treatments or exposures are preferentially given to specific groups based on prognosis.

What is protopathic bias?

when a treatment is initiated for early symptoms of a disease not yet diagnosed, confusing cause and effect.