HSC 404 - FINAL EXAM (CH 9, 10, 11, 12, 13, 15, 16)
QUESTIONS AND ANSWERS SOLVED 100% CORRECT!!
The strategy which is not aimed at reducing selection bias is:
A. Development of an explicit case definition
B. Standardized protocol for structured interviews
C. Enrollment of all cases in a defined time and region
D. Encouragement of high participation rates Answer - D
Recall bias is most likely to occur in:
A. Case control studies
B. Prospective cohort studies
C. Experimental studies
D. All of the above
E. None of the above Answer - A
The purpose of a double-blind study is to:
A. Reduce the effects of sampling variation
B. Avoid observer bias and sampling variation
C. Achieve comparability of cases and controls
,D. Avoid observer and interviewee bias
E. Avoid interviewee bias and sampling variation Answer - D
In a study to determine the incidence of chronic disease, 150 people were
examined at the end of a three-year period. Twelve cases were found, giving a
cumulative risk of 8%. Fifty other members of the initial cohort could not be
examined; 20 of these 50 could not be examined because they died.
Which source of bias may have affected the study?
A. Information bias: interviewer/abstractor bias
B. Hawthorne Effect
C. Selection bias: survival bias
D. Information bias: recall bias Answer - C
Which of the following is not a type of selection bias in cohort studies:
A. Loss to follow-up
B. None of the above
C. Healthy worker effect
D. Interviewer bias Answer - D
Surgeons at Hospital A report that the mortality rate at the end of a one-year
follow-up after a new coronary bypass procedure is 15%. At Hospital B, the
surgeons report a one-year mortality rate of 8% for the same procedure. Before
concluding that the surgeons at Hospital B have vastly superior skill, which of
the following possible confounders would you examine? Answer - A. The
severity (stage) of the disease of the patients at the two hospitals at baseline
B. The starting point of the one-year follow-up at both hospitals
, C. Different in the post-operative care at the two hospitals
D. Equally through follow-up for mortality
E. All of the above
E
Which of the following is not a method for controlling the effects of
confounding in epidemiologic studies?
A. Matching
B. Randomization
C. Stratification
D. Restriction
E. Blinding Answer - E
An epidemiologic experiment is performed in which one group is exposed to a
suspected factor and the other is not. All individuals with an odd hospital
admission number are assigned to the second group.
The main purpose of this procedure is to: Answer - A. Prevent observer bias
with respect to the factor
B. Prevent observer bias with respect to the outcome
C. Improve the likelihood that the two groups will be comparable with regard
to known and unknown confounding factors.
D. Ensure a double-blind study
E. Guarantee comparability of the two groups with regard to other relevant
factors
QUESTIONS AND ANSWERS SOLVED 100% CORRECT!!
The strategy which is not aimed at reducing selection bias is:
A. Development of an explicit case definition
B. Standardized protocol for structured interviews
C. Enrollment of all cases in a defined time and region
D. Encouragement of high participation rates Answer - D
Recall bias is most likely to occur in:
A. Case control studies
B. Prospective cohort studies
C. Experimental studies
D. All of the above
E. None of the above Answer - A
The purpose of a double-blind study is to:
A. Reduce the effects of sampling variation
B. Avoid observer bias and sampling variation
C. Achieve comparability of cases and controls
,D. Avoid observer and interviewee bias
E. Avoid interviewee bias and sampling variation Answer - D
In a study to determine the incidence of chronic disease, 150 people were
examined at the end of a three-year period. Twelve cases were found, giving a
cumulative risk of 8%. Fifty other members of the initial cohort could not be
examined; 20 of these 50 could not be examined because they died.
Which source of bias may have affected the study?
A. Information bias: interviewer/abstractor bias
B. Hawthorne Effect
C. Selection bias: survival bias
D. Information bias: recall bias Answer - C
Which of the following is not a type of selection bias in cohort studies:
A. Loss to follow-up
B. None of the above
C. Healthy worker effect
D. Interviewer bias Answer - D
Surgeons at Hospital A report that the mortality rate at the end of a one-year
follow-up after a new coronary bypass procedure is 15%. At Hospital B, the
surgeons report a one-year mortality rate of 8% for the same procedure. Before
concluding that the surgeons at Hospital B have vastly superior skill, which of
the following possible confounders would you examine? Answer - A. The
severity (stage) of the disease of the patients at the two hospitals at baseline
B. The starting point of the one-year follow-up at both hospitals
, C. Different in the post-operative care at the two hospitals
D. Equally through follow-up for mortality
E. All of the above
E
Which of the following is not a method for controlling the effects of
confounding in epidemiologic studies?
A. Matching
B. Randomization
C. Stratification
D. Restriction
E. Blinding Answer - E
An epidemiologic experiment is performed in which one group is exposed to a
suspected factor and the other is not. All individuals with an odd hospital
admission number are assigned to the second group.
The main purpose of this procedure is to: Answer - A. Prevent observer bias
with respect to the factor
B. Prevent observer bias with respect to the outcome
C. Improve the likelihood that the two groups will be comparable with regard
to known and unknown confounding factors.
D. Ensure a double-blind study
E. Guarantee comparability of the two groups with regard to other relevant
factors
