Question 1

In a hypothetical case‐control study with perfect measurement, the association between occupational resin exposure and lung cancer was OR=1.76.The data for this
Association is provided in the Table below:  What would the OR be if 10% of all those exposed had been misclassified as
Unexposed, and 10% of all those unexposed had been misclassified as exposed?

Accepted Answer

A)  1.33
B)  1.51
C)  0.99
D)  1.55 B

Question 2

What term best describes the misclassification in the previous question?

Accepted Answer

A)  Differential
B)  Non‐differential
C)  Systematic
D)  None of the above B

Question 3

In prospective cohort studies, why is loss to follow‐up a source of selection bias?

Accepted Answer

A)  The study will no longer be representative of the general population
B)  It reduces the size of the study sample
C)  Those lost to follow‐up may have different characteristics to those who remain in the study
D)  Those who are lost to follow‐up may recall things differently from those who remain in the study
E)  There is more likely to be ascertainment bias when measuring outcomes in those who remain in the study C

Question 4

In a case‐control study of the association between residence near a hazardous waste site and leukaemia, selection bias is likely to be a problem because:

Accepted Answer

A)  People with leukaemia may be more likely to participate than controls recruited from the general population
B)  People with leukaemia living near a hazardous waste site may be more likely to participate than people living further away.
C)  People without leukaemia living near a hazardous waste site may be more likely to participate than people living further away
D)  All of the above

Question 5

You want to assess the effects of physical activity on study habits so you advertise at your local university for people to take part in your study.What type of selection bias
Might this lead to?

Accepted Answer

A)  Loss to follow‐up
B)  Volunteer bias
C)  Recall bias
D)  Observer bias
E)  None of the above

Question 6

What term best describes the misclassification in the previous question?

Accepted Answer

A)  Differential
B)  Non‐differential
C)  Random
D)  None of the above

Question 7

What would the OR have been if 10% of cases who were unexposed were misclassified as exposed, but all other groups were measured accurately?

Accepted Answer

A)  1.33
B)  0.99
C)  2.34
D)  1.55

Question 8

To determine attack rates for a respiratory disease of unknown origin among people attending a conference, random samples of guests staying at four hotels were
Surveyed for subsequent illness.Because it was not feasible to survey all guests,
Random sampling provided the best information because:

Accepted Answer

A)  It would identify all cases of disease
B)  It would avoid selection bias
C)  It would reduce measurement bias
D)  It would eliminate sampling error
E)  It would eliminate confounding

Question 9

In measuring an exposure in a prospective cohort study design, which biases are most readily avoidable?

Accepted Answer

A)  Misclassification
B)  Interviewer bias
C)  Recall bias
D)  Healthy worker effect
E)  None of the above

Question 10

A study was conducted to determine the side effects of 4 anti‐malarial drugs in a group of overseas volunteers in Cameroon.A self‐report questionnaire was given to each
Participant and participation was voluntary.Each participant was asked to indicate
Which drugs they had used and the severity of any side effects they had experienced
Over the past two years.What kind(s) of bias would most likely be present in this
Study? (Select all that apply)

Accepted Answer

A)  Interviewer bias
B)  Recall bias
C)  Observer bias
D)  Misclassification
E)  Volunteer bias

Exam 7: All That Glitters Is Not Gold: The Problem of Error

What term best describes the misclassification in the previous question?

In prospective cohort studies, why is loss to follow‐up a source of selection bias?

In a case‐control study of the association between residence near a hazardous waste site and leukaemia, selection bias is likely to be a problem because:

You want to assess the effects of physical activity on study habits so you advertise at your local university for people to take part in your study.What type of selection bias Might this lead to?

What term best describes the misclassification in the previous question?

What would the OR have been if 10% of cases who were unexposed were misclassified as exposed, but all other groups were measured accurately?

To determine attack rates for a respiratory disease of unknown origin among people attending a conference, random samples of guests staying at four hotels were Surveyed for subsequent illness.Because it was not feasible to survey all guests, Random sampling provided the best information because:

In measuring an exposure in a prospective cohort study design, which biases are most readily avoidable?