Confounding Bias

Question 1

define what a confounder is

Answer 1

a variable that is causally related to the outcome variable of interest and associated with the exposure of interest but is not an intermediate variable

Question 2

T/F there is no statistical test for confounding

Answer 2

True

Question 3

define bias

Answer 3

SYSTEMATIC error in the design, conduct or analysis that results in an inaccurate estimate of the measure of effect

Question 4

T/F bias is random error

Answer 4

false

Question 5

what is selection bias?

Answer 5

individuals have different probabilities of being sampled according to relevant study variables

Question 6

what is information bias?

Answer 6

Study data are collected in a manner that results in inaccurate measurements of disease, exposure, etc.

Question 7

what is volunteer bias?

Answer 7

Reasons why people volunteer may be related to study variables

Question 8

what is non-response bias?

Answer 8

Persons who agree to participate in a study/respond to a questionnaire may be different than those who refuse

Question 9

what is detection bias?

Answer 9

People with exposure more likely to be identified, generally due to increased medical surveillance, and are thus more likely to have the disease identified

Question 10

what is lead-time bias

Answer 10

when survival time appears longer because diagnosis was done earlier, irrespective of whether the patient lived longer. results due to earlier detection, not delayed death

Question 11

what is length-time bias

Answer 11

Individuals with a long preclinical phase of disease more likely to be identified and more likely to have a better prognosis

Question 12

what is berkson’s bias (hospital patient bias)

Answer 12

using hospitalized controls can effect results of study due to hospitalized patients likely having different sick factors compared to the general population

Question 13

what is loss to follow-up bias?

Answer 13

occurs in cohort studies or RCTs, when patients drops out of the study

Question 14

what is survivorship bias?

Answer 14

Persons with longer survival time have more opportunity to be selected for a study compared to people with aggressive, rapid forms of disease that lead to earlier mortality

Question 15

what is recall bias?
which study design type is it most often seen in?

Answer 15

persons with and without outcome have different recall of prior exposures
case-control studies

Question 16

what is reporting bias?

Answer 16

Study subjects may knowingly falsify data because of social stigma, beliefs, attitudes, etc.

Question 17

all biases are considered selection bias except for which 3? What type of bias are those 3 considered?

Answer 17

misclassification, recall, and reporting bias

Information biases

Question 18

which forms of bias could occur in a prospective cohort study?

Answer 18

volunteer, non-response, loss to follow-up, survivorship, chanelling, misclassification

Question 19

which forms of bias could occur in a retrospective cohort study?

Answer 19

length-time, berkson’s, chanelling, misclassification