Bias Flashcards
1
Q
Selection bias
(Sampling bias)
A
- Nonrandom assignment into groups leading to unrepresentative sample
- Non-generalizable
- Ex: study population selected from hospital is generally less healthy
2
Q
Recall Bias
A
- Knowledge of presence of disease changes subject’s response
- Common in retrospective studies
3
Q
Measurement Bias
A
- Information is gathered in a way that distorts it
- Ex: miscalibrated scale
4
Q
Procedure Bias
A
- Subjects in different groups not treated the same
- Ex: patients in treatment group spend more time in specialized units
5
Q
Observer Bias
A
- Researcher’s decision affected by prior knowledge of subject’s exposure status
6
Q
Hawthorne Effect
A
- Subjects change behavior when they know they’re being studied
- Subject’s behavior
7
Q
Confounding Bias
A
- One factor distorts/confuses the effect of another closely related one
- Factor is related to both exposure and outcome, but is not in causal path
8
Q
Lead-time Bias
A
- Early detection confused with increased survival
- Early detection makes it seem like survival has increased, but natural course of disease has not changed
- Seen in screening trials
9
Q
Selection bias can lead to what type of error?
A
both type 1 and type 2
10
Q
Small samples decrease power, which can lead to what type of error?
A
type 2
- increases the effect of random error, which bias toward the null
11
Q
Non-compliance can lead to what type of error?
A
Type 2
bias toward the null
12
Q
Co-interventions in a control group can lead to what kind of error?
A
Type 2
bias toward the null
13
Q
Co-interventions in a treatment group can lead to what kind of error?
A
Type 1
14
Q
If you decrease prevalence, what happens to the +PV?
A
decreases
15
Q
General advantages of cohort studies:
A
- assess exposure and potential confounders at the same time
- can study multiple outcomes
- less recall bias and selection bias
- directly measure RR and AR
