Biases Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Selection bias

A

Nonrandom sampling of participants. ex, selected based on adherence to medicines or other criteria that can affect the outcome of the study.

Includes Berkson bias
Health worker effect
Non-response bias

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Berkson bias

A

Study population selected from a hospital is less healthy than the general population

a type of selection bias

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Healthy worker effect

A

The study population is more healthy than the general population

a type of selection bias

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Non-response bias

A

The subjects that participated are different from the non-responders in important ways.

a type of selection bias

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Recall bias

A

Seen in retrospective studies.

Awareness of the disorder affects peoples recall. After learning more about their disease they are more likely to ‘remember’ significant exposures.

Minimize this by decreasing the time from exposures to follow up.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Measurement bias

A

Information is gathered in a non-standardized manner. Different criteria at different times/places.

Hawthorne effect is part of it.
People behave differently when they know they’re being observed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Procedure bias.

A

Subjects in different groups are not treated the same.

ex. people in the treatment group spend more time in specialized hospital units than those in the non-treatment group.

Reduce by using Blinding of patients and researchers and Placebos.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Observer-expectancy bias

A

Th researchers beliefs about the treatment affect the outcome. If he expects recover he documents it more often.

Reduce by using blinding and placebos.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Confounding bias

A

When an outside factor is related to both the exposure and the outcome.
ex. coal workers get lung cancer more often but coal workers also smoke more often.

Reduce by repeating studies.
Crossover studies with subjects being their own controls
Matching patients with similar characteristics in the control and treatment/exposure group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Lead-time bias

A

Early detection is mistaken for longer survival.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly