Lecture 5: Bias & Misclassification Flashcards Preview

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Flashcards in Lecture 5: Bias & Misclassification Deck (33)
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1

what 3 aspects of a study, must researchers evaluate for internal validity before they can declare a true association?

1. confounders and effect modifiers
2. bias and misclassification
3. statistical significance

2

definition of bias

systematic error in study design or conduct, resulting in false results

3

how do we control for bias after a study has been conducted?

we can't

must be done before study is implemented

4

what are the 3 elements of bias impact?

1. source or type
2. magnitude
3. direction

5

the 2 main categories of bias

selection-related
measurement-related

6

selection-related bias

any aspect in the way the researcher selects study subjects differently

7

measurement-related bias

any aspect in the way the researcher collects data differently

8

types of selection bias

healthy-worker bias
self-selection bias

9

other names for responder bias

self-selection bias
participant bias

10

what type of bias is easily seen in prospective cohort studies?

healthy-worker bias

11

measurement bias can be ……?

subject related
observer related
screening related

12

subject related bias

type of measurement bias
recall bias
hawthorne effect
contamination bias
compliance bias
lost to follow up bias

13

groups being studied have different withdrawal rates

lost to follow up bias

14

groups being interventionally studied have different adherence with study protocols

compliance/adherence bias

15

members of the control group, receive treatment or are exposed to the intervention being studied

contamination bias

take drugs they shouldn't

16

individuals alter their behavior because they know they are apart of a study under observation

hawthorne effect
or
observer effect

17

a differential level of accuracy in provided information between study groups

recall bias or reporting bias

18

observer-related

type of measurement bias
interviewer bias
surveillance bias

19

a systematic difference in interpreting done by the researcher

interviewer bias
not always consciously done

20

different evaluation or diagnosis between study groups due to an observers expectations

diagnosis/surveillance/expectation bias

21

screening-related

type of measurement bias
lead-time bias

22

an apparent benefit from a healthcare screening due to the early detection of disease despite an unchanged clinical outcome

lead-time bias

23

source of measurement bias, especially observer-related bias

misclassification bias

24

error in classifying either disease or exposure status, or both

misclassification

25

the 2 types of misclassification

differential
non-differential

26

misclassification of exposure which is unrelated to the other exposure

non-differential = error in both groups equally

27

not different

non-differential

28

in non-differential bias, the measure of association is always....?

type of misclassification
OR is always moved towards 1.0

29

misclassification of exposure which is related to the other exposure

differential misclassification

30

in differential bias, the measure of association is.....?

can be inflated or depreciated

31

ways to control for bias

blinding/masking
multiple data sources
randomly allocate observers for data collection
minimize loss to follow up bias

32

random allocation and randomization are ways to control for....?

random = bias control
randomization = confounding control

33

ways to control for confounding variables

restriction
randomization
matching
stratification
multivariate analysis