Study Design
Researchers were interested in the potential anti-carcinogenic (cancer-preventing) properties of soy protein. For each of 47 districts in Japan, stomach cancer mortality rates were obtained from the National Vital Statistics, 1995. For the same 47 districts, average per capita soy product intake was obtained from the National Nutritional Survey Report 1980–1985. What type of study was this?
a. Ecological study
b. Experimental study (clinical trial)
c. Retrospective cohort study
d. Cross-sectional study
e. Case-control study
f. Prospective cohort study
a. Ecological study
What measure of association do we calculate from a case control study?
a. Relative Risk
b. Incidence
c. Attributable Risk
d. Odds Ratio
e. Prevalence
d. odds ratio
A cohort study of coffee drinking and insomnia was conducted at a university campus. Suppose that the risk ratio for insomnia in coffee drinkers was 3.7. Which of the following would be the best interpretation of this risk ratio?
A. The risk of insomnia is 3.7 times greater among coffee drinkers compared with the general campus population
B. The risk of insomnia is 3.7 times greater among coffee drinkers compared with non-coffee drinkers
C. The excess risk of insomnia among the university population is 3.7%
B. The risk of insomnia is 3.7 times greater among coffee drinkers compared with non-coffee drinkers
In a case-control study of passive smoke exposure and asthma, newly diagnosed asthma cases were compared with a random sample of controls drawn from the total population that produced the cases. Cases and controls were asked a series of questions designed at assessing the extent to which they had been exposed to passive (i.e., environmental) smoke in the past, either at home or in other settings. You are concerned that people with asthma are more aware of their exposure to passive smoke than those without asthma. What type of bias would this produce? (Select one.)
A. Self-selection bias
B. Loss to follow-up bias
C. Recall bias
D. None of the above
C. Recall bias
Confounding can cause either an overestimate or and underestimate of the true association.
a. True
b. False
a. True
Case-control studies are efficient for studying multiple health effects (diseases) stemming from a single exposure.
a. True
b. False
b. False
The following statement is taken from an article that recently appeared in the New York Times entitled, “With Soap and Water or Sanitizer, a Cleaning That Can Stave Off the Flu”. "In a troubling finding, a recent study of 404 British commuters found that 28 percent had fecal bacteria on their hands." The 28% represents which of the following measures of disease frequency?
A. Prevalence
B. Incidence
C. both
D. neither
A. Prevalence
A cohort study of coffee drinking and anxiety was conducted at a university campus. Suppose that the excess risk of anxiety among coffee drinkers was 7 per 100 over 5 years. Which of the following would be the best interpretation of this risk difference?
A. Coffee drinkers are 7 times as likely to develop anxiety as compared to non-coffee drinkers
B. The excess risk of anxiety among among coffee drinkers is 7 per 100 over five years as compared to non-coffee drinkers
C. The excess risk of anxiety among the entire freshmen population is 7 per 100 over five years.
D. Coffee drinkers have 7% more anxiety compared to non-coffee drinkers.
B. The excess risk of anxiety among among coffee drinkers is 7 per 100 over five years as compared to non-coffee drinkers
Which of the following is NOT a type of information bias?
a) Loss to follow up
b) Recall bias
c) Interviewer bias
d) Prevarication (lying) bias
Which is NOT one of the three criteria for a confounder?
a) Must be a risk factor for disease
b) Must be associated with exposure
c) Must not be an intermediate step in the causal pathway between exposure and disease
d) Must occur in a case-control or cohort study
d. Must occur in a case-control or cohort study
Which of the following is true of a cohort study?
1. A major advantage is that it can indicate the temporal sequence between exposure and outcome.
2. Differential loss to follow-up according to exposure or outcome status cannot occur in a retrospective cohort study.
3. Cohort studies are not useful for evaluating multiple outcomes.
4. Cohort studies are very useful for evaluating rare diseases.
1. A major advantage is that it can indicate the temporal sequence between exposure and outcome.
What is the correct formula for Relative Risk/IRR?
a. Incidence rate in the exposed / Incidence rate in the non-exposed
b. Incidence rate in the diseased / Incidence rate in the non-diseased
c. Risk in exposed / Risk in unexposed
d. Proportion of those diseased within the sample population
e. Proportion of exposed in within the sample population
a. Incidence rate in the exposed / Incidence rate in the non-exposed
Researchers were interested in conducting a study on the efficacy of a new HIV drug (Dovato) against the current standard of care. The randomized trial was performed over 9 years. The trial compared the efficacy of HIV treatment of Dovato compared to the current standard of care. Patients with HIV at multiple health clinics in San Francisco were recruited for the trial and randomized into treatment groups. The calculated % relative effect was 163%. Interpret this measure.
a. In this 9-year study in San Francisco, the cure rate for HIV was 163% higher/greater among the Dovato treated group compared to those who received the standard of care treatment.
b. In this 9-year study in San Francisco, the Dovato treated group was 163 times more likely to be cured of HIV than the standard of care group.
c. In this 9-year study in San Francisco, the odds of being cured of HIV was 63 times greater among those treated with Dovato.
d. In this 9-year study in San Francisco, those treated with standard course of treatment were 63 times more at risk of not being cured of HIV.
a. In this 9-year study in San Francisco, the cure rate for HIV was 163% higher/greater among the Dovato treated group compared to those who received the standard of care treatment.
A participant refuses to participate in the study based on their own disease status. What type of bias does this describe?
a. Control selection bias
b. Self selection bias
c. Healthy worker effect
d. Information bias
b. self selection bias
Select ALL of the methods to control for confounding in the DESIGN stage:
a. Stratified analysis
b. Matching
c. Randomization
d. Standardization
e. Multivariate analysis
f. Restriction
b, c, f (matching, randomization, restriction)
What are some major disadvantages of ecological studies? (multiple answers)
a. cannot determine temporality of disease/exposure
b. data is collected at the group level and therefore, it may not represent the exposure-disease relationship at the individual level
c. cannot study disease etiology
d. possible confounding
All of the above
a. cannot determine temporality of disease/exposure
b. data is collected at the group level and therefore, it may not represent the exposure-disease relationship at the individual level
c. cannot study disease etiology
d. possible confounding
The MA Department of Public Health Reports that the Population Attributable Risk Percent (PAR%) for motor vehicle fatalities as a result of not wearing a seat belt is 17%. The correct interpretation of this PAR% is:
A. Assuming association is causal, 17% of those who fail to wear seat belts and died in motor vehicle accidents died as a result of not wearing a seat belt
B. If failure to wear a seat belt were eliminated in Massachusetts, one would expect the rate of motor vehicle fatalities to fall by 17%
C. 83% of those who die in motor vehicle accidents die as a result of failing to wear a seat belt
B. If failure to wear a seat belt were eliminated in Massachusetts, one would expect the rate of motor vehicle fatalities to fall by 17%
A study was conducted to see whether taking folic acid during pregnancy had an effect on the incidence of neural tube defects (NTDs) in newborns. We calculated a rate ratio of 0.613. Which of the following is the best interpretation of this rate ratio using percent relative effect?
a) Mothers who received folic acid during pregnancy had a 61.3% reduction in the incidence of newborn NTD compared to mothers who did not receive folic acid during pregnancy.
b) Mothers who received folic acid during pregnancy had a 38.7% reduction in the incidence of newborn NTD compared to mothers who did not receive folic acid during pregnancy.
c) Mothers who received folic acid during pregnancy had a 38.7% increase in the incidence of newborn NTD compared to mothers who did not receive folic acid during pregnancy.
b. (Rate Ratio - 1) x 100 = (0.613 - 1) x 100 = -0.387x 100 = -38.7%
38.7% reduction, Mothers who received folic acid during pregnancy had a 38.7% reduction in the incidence of newborn NTD compared to mothers who did not receive folic acid during pregnancy.
Retrospective cohort studies and case-control studies tend to be more vulnerable to bias, because both exposures and outcomes have already occurred by the time the study begins.
a. True
b. False
a. True
Select ALL of the methods to control for confounding in the ANALYSIS stage:
a. Stratified analysis
b. Matching
c. Randomization
d. Standardization
e. Multivariate analysis
f. Restriction
a, d, e (stratified analysis, standardization, multivariate analysis)
For the following questions, identify which of the following five types of study designs most appropriately characterizes each of the situations described below? A particular study design may be selected once, more than once, or not at all but there is only one correct answer to each question.
50 children, 5-10 y.o, recently diagnosed with asthma were selected from an outpatient pediatric clinic along with another group of 40 similarly aged children without asthma. The mother of each child was interviewed to determine whether any household member smoked during the first 2 years of the child’s life
A. Cross-sectional study
B. Case-control study
C. Prospective cohort study
D. Retrospective (Historical) cohort study
E. Clinical Trial
F. Community trial
G. Ecological
B. Case-control study
For the following questions, identify which of the following five types of study designs most appropriately characterizes each of the situations described below? A particular study design may be selected once, more than once, or not at all but there is only one correct answer to each question.
It has been suggested that high exposure to heavy metals such as lead may increase long-term risks of Alzheimer’s disease. Epidemiologists in Britain were commissioned by a battery company to determine whether heavy metal exposure at the plant increased the risk of developing dementia later in life. 1,500 former employees were randomly selected from company records. These employees’ levels of occupational lead exposure over the previous 20 years had been recorded and were available in company records. The epidemiologists reviewed each subjects exposure data and then obtained current medical records to determine how many of them had been diagnosed with Alzheimer’s in the past five years.
A. Cross-sectional study
B. Case-control study
C. Prospective cohort study
D. Retrospective (Historical) cohort study
E. Clinical Trial
F. Community trial
G. Ecological
For the following questions, identify which of the following five types of study designs most appropriately characterizes each of the situations described below? A particular study design may be selected once, more than once, or not at all but there is only one correct answer to each question.
Evidence of a link between coffee consumption and gall bladder disease was sought among a sample of 1,123 men and women in Vienna, Austria. These men and women completed a questionnaire regarding coffee drinking habits and submitted to an examination of their gall bladder for evidence of disease.
A. Cross-sectional study
B. Case-control study
C. Prospective cohort study
D. Retrospective (Historical) cohort study
E. Clinical Trial
F. Community trial
G. Ecological
A. Cross-sectional study