Article - The Environment and Disease: Association or Causation? by Sir Austin Bradford Hill
QUESTION 1: A systematic error in the design or conduct of a study that results in an incorrect estimate of an exposure's effect on the risk of the outcome is called:
Confounding
Bias
Stratification
Effect modification
QUESTION 2: If a correlation were observed between per capita soft drink consumption and incidence of pancreatic cancer by country, this correlation, while possibly suggestive of a real association (that could be studied further with more analytic studies) would be subject to:
The ecologic fallacy
Differential recall bias
Non-differential recall bias
Effect modification
QUESTION 3: Either factor A or B can cause a certain disease, but only when followed by exposure to factor Z. Exposure to factor Z alone is not followed by disease, but the disease never occurs in the absence of exposure to factor Z. Factor Z is:
Necessary and sufficient
Necessary but not sufficient
Sufficient but not necessary
Neither necessary nor sufficient
QUESTION 4: Referring to the scenario above, factor B is:
Necessary and sufficient
Necessary but not sufficient
Sufficient but not necessary
Neither necessary nor sufficient
QUESTION 5: A hypothetical cohort study included 10,000 exposed and 10,000 unexposed people. Among the exposed, 500 got the disease.Among the unexposed, 100 got the disease. What is the relative risk of disease among those exposed relative to those not exposed?
4.0
4.21
5.0
5.21
QUESTION 6: Referring to the scenario above assume that 20% of those who were exposed AND diseased were lost to follow-up. What would be the observed relative risk of disease among those exposed relative to those not exposed?
3.17
4.00
4.04
4.17
QUESTION 7: A strategy which is not aimed at reducing selection bias is:
Development of an explicit case definition
Encouragement of high participation rates
Standardized protocol for structured interviews
Enrollment of all cases in a defined time and region
QUESTION 8: The purpose of a double-blind study is to:
Achieve comparability of cases and controls
Reduce the effects of sampling variation
Avoid observer and subject bias
Avoid observer bias and sampling variation
QUESTION 9: Suppose that a case-control study is done in which the cases are more likely than the controls to remember and accurately provide information about their exposure. This is an example of:
Non-differential misclassification bias
Differential misclassification bias
Selection bias
Exclusion bias
QUESTION 10: The null hypothesis refers to the assumption that there is no difference between treatment/exposure groups with regard to the outcome of interest. If the true relative risk is 5 and the estimated relative risk is 2, the direction of bias would be:
Toward the null
Away from the null
Switch over
Cannot be determined
QUESTION 11: If the true relative risk is 0.7 and the estimated relative risk is 0.3, the direction of bias would be:
Toward the null
Away from the null
Switch over
Cannot be determined
QUESTION 12: Methods to reduce information bias include all the following except:
Training of interviewers
Standard data collection form
Blinding of interviewers
Consistent case definition
QUESTION 13: In order for a factor to be a confounder it must:
be associated with the exposure
be associated with the outcome
not in the causal chain
all of the above
QUESTION 14: Methods to control for a confounding variable in the design stage include all the following except:
matching
randomization
restriction
adjustment
QUESTION 15: Which of the following techniques can be used to control for confounding in the analysis stage of a study?
randomization
stratification
effect modification
blinding
QUESTION 16: A hypothetical case-control study was done to examine the association between coffee consumption and anorexia among teenagers. The odds ratios, comparing the odds of frequent coffee consumption among teenagers who have anorexia to the odds of frequent coffee consumption among teenagers who do not have anorexia, are shown in the following table:
Odds ratios
Both sexes 5.1
Males 1.5
Females 1.5
Based only on these results, which of the following statements would apply:
gender is a confounder
coffee consumption is a confounder
the risk of anorexia is the same in males and females
gender is an effect modifier
QUESTION 17: Surgeons at Hospital A report that the mortality rate at the end of a 2-year follow-up after a new surgical procedure is 20%. At Hospital B, the surgeons report a 2-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?
The severity (stage) of disease of the patients at the two hospitalsat baseline
The starting point of the follow-up (after operation versus after discharge)
The difference in the post-operative care at the two hospitals
All of the above
The commentary by Sir Austin Bradford Hill (1965), in which he describes criteria for judging whether an observed association is causal remains one of the most influential texts in the epidemiological literature. The guidelines offered by Gordis in the course text (pp. 236239) essentially restate those concepts. Bradford Hill's original criteria (and the corresponding contemporary guidelines of Gordis) are as follows:
a. Strength (strength of the association)
b. Consistency (replication of the findings)
c. Specificity (specificity of the association)
d. Temporality (temporal relationship)
e. Biological gradient (dose-response relationship)
f. Plausibility (biologic plausibility)
g. Coherence (consistency with other knowledge)
h. Experiment (cessation of exposure)
i. Analogy (consideration of alternate explanations)
For each definition identified in questions 18 through 21, indicate the Bradford Hill criterion it most closely describes.
QUESTION 18: The association can be explained in terms of known biologic mechanisms.
Strength
Consistency
Specificity
Temporality
Biological gradient
Plausibility
Coherence
Experiment
Analogy
QUESTION 19: Findings in a study indicated that the greater the exposure to tobacco the greater the risk of lung cancer.
Strength
Consistency
Specificity
Temporality
Dose Response
Plausibility
Coherence
Experiment
Analogy
QUESTION 20: Exposure must precede the outcome.
Strength
Consistency
Specificity
Temporality
Biological gradient
Plausibility
Coherence
Experiment
Analogy
QUESTION 21: An increase in the level, intensity, or duration of exposure is associated with increases in the magnitude of the risk.
Strength
Consistency
Specificity
Temporality
Biological gradient
Plausibility
Coherence
Experiment
Analogy
Attachment:- Assignment.rar