Review Questions for Chapter 8 Last Update: 11/15/2008  

§8.1 Introduction (Basics)

  1. This term is used to refer to the explanatory variable in an epidemiologic study.
  2. This term is used to refer to the response variable or "outcome".
  3. [T/F] The terms "measure of association" and "measure of effect" are used  interchangeably. 
  4. What does it mean when we say there is a positive association between an exposure and disease?
  5. [T/F] Associations equals causation.
  6. [T/F] Absolute comparisons are made by division.
  7. [T/F] Relative comparisons are made by division. 
  8. [T/F] When I say, "there will be 5 additional cases per 1000 exposure" I am referring to an RR.
  9. [T/F] When I say, "the exposure doubles risk" I am referring to a RR.
  10. This statistic quantifies the effect of an exposure in absolute terms. 
  11. This statistic quantifies the effect of an exposure in relative terms. 
  12. An exposed group has a risk of 50% and a non-exposed group has a risk of 35%. What is the RD?  
  13. Same data as prior question; what is the RR? 
  14. A report states "people who do not wear seat belts are eight times as likely to die in an automobile accident." Is this an example of an incidence, prevalence, relative risk, or risk difference?
  15. The one-year risk in an exposed group is 15 per 1000. The one-year risk of disease in a nonexposed is 10 per 1000. Would it be correct say that the exposure increases risk by 150%? Explain your reasoning..
  16. An RR of 1.4 suggests risk increases by ______% with exposure. 
  17. [T/F] A RR of 0.7 indicates a positive association between the exposure and disease. 
  18. [T/F] A RD of 0.7 per 100 indicates a positive association between the exposure and disease.
  19. [T/F] The baseline RR is 1.
  20. [T/F] The baseline RD is 1. 

§8.2 Absolute Measures of Association

  1. [T/F]: An incidence proportion difference is also called a risk difference.
  2. [T/F]: An incidence rate difference is also called a incidence density difference.
  3. What happens to the RD  if we redefine the exposed group as non-exposed group and vice versa?
  4. The rate difference for the illustrative example on p. 159 for improved physical fitness and overall mortality is ­54.3 per 10,000 person-years. Interpret this statistic. 

§8.3 Relative Measures of Association

  1. List two technical synonyms for risk ratio.
  2. List two technical synonyms for rate ratio.
  3. If we redefine the exposed group as the non-exposed group, what is the effect on the risk difference?
  4. A risk ratio is 1.85. How much does the exposure increase risk in relative terms? 
  5. Under what conditions will a rate ratio equal a risk ratio?
  6. Under what conditions will a prevalence ratio equal a risk ratio?

§8.4 Measures of Potential Impact 

  1. This statistic describes the potential reduction in incidence if we removed exposure from exposed cases.
  2. According to Table 8.7, we could reduce overall cancer mortality by about 50% if we modified these two factors in the population.
  3. Why does the sum of attributable fractions for a disease equal more than 100%?
  4. Explain how the AFp differs from the AFe. 
  5. Matching. Terms: RR, RD, AF 
    Descriptions:
    (a) quantifies effect in absolute terms
    (b) quantifies effect in relative terms
    (c) quantifies proportion of cases that would be averted with removal of the exposure

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