Review Questions for Chapter 16

§16.1 Introduction

  1. Why is it necessary to base preventive measures on correct knowledge of cause? 
  2. What is causal inference? (Define.)
  3. Is there such thing as ultimate proof in empirical sciences?
  4. True or false? Despite difficulties in inference, much of what we know about human health and disease comes from observational studies.
  5. What is the goal of causal inference in public health?
  6. Describe the two types of decisions in epidemiology and identify how they differ. 
  7. Provide an example in which the discovery of an effective preventive measure predated the discovery of the causal mechanism.
  8. In your opinion, is there any such thing as the scientific method?
  9. What is induction? 
  10. Describe "The Problem of Induction".
  11. True or false? According to refutationist philosophy, the value of a scientific hypothesis depends on the degree to which it can be disproved.
  12. Why can you never scientifically prove that "all swans are white?"
  13. Describe the asymmetry of positive proof and negative proof. 

§16.2 Advisory Committee to the Surgeon General on Smoking and Health

  1. What type of evidence besides epidemiologic studies are used to support causal arguments? 
  2. True of false? Multiple factors and variables must be considered when studying cause and effect. 
  3. True of false? Association = causation
  4. True of false? Statistical methods cannot establish proof of a causal relation.
  5. List causal criteria presented in the The Surgeon General's Report of 1964. 
  6. In what year was the first U.S. Surgeon General's Report on Smoking and Health written?

§16.3 Hill's Framework

  1. What is the most direct epidemiologic measure of the strength of association?
  2. Why do strong associations provide firmer causal evidence than weak associations?
  3. Are weak associations indicative of non-causality?
  4. If many studies show similar results, does this prove the association is causal?
  5. Do you agree with this statement? Specificity is a powerful criteria in support of causality. Explain and qualify.
  6. True of false? Establishing the proper temporal relation between cause and effect is a mandatory causal criteria. 
  7. Describe possible reasonable temporal relations between the factors of deficient care-giving, environmental lead exposure, intellectual impairment in children, and pica in children. 
  8. Provide an example of an inverted U shape risk between an environmental exposure and the risk of a disease.
  9. The slang expression "reality test" is most akin to which of Hill's causal criteria?
  10. How does the criteria of coherence differ from the criteria of plausibility?
  11. List the types of experiments potentially available to the epidemiologic investigator. 
  12. Early in the HIV epidemic of the early 1980s, epidemiologists realized high risk HIV groups were also high risk Hepatitis B groups. This lead some to suggest HIV was an infectious disease. (The other popular hypothesis at the time was that HIV was caused by an environmental toxin, such as "poppers.") What criteria is being addressed here.
  13. A study on micro-nutrient levels and Alzheimer's disease found progressively lower risks of brain atrophy (shrinkage) associated with step-wise increases  in folic acid (Snowdon et al., 2000). Which of Hill's criteria does this address?
  14. List the brief labels the text uses to identify each of Hill's causal "criteria."
  15. The association between oral contraceptive use and clotting diseases has been the subject of considerable epidemiologic debate. Below are statements that helped bolster causal arguments on this subject. In each instance, select the SINGLE best criterion addressed by the statement. 

    Criterion: (a) Strength (b) Consistency (c) Specificity (d) Temporality (e) Biological Gradient (f) Plausibility

    Statements: 
    (1) The rate of cardiovascular disease increases progressively with higher doses of estrogen in oral contraceptive formulations.
    (2) Lab studies show that oral contraceptive use increases coagulability of blood .
    (3) Studies from the 1970s suggest early formulations triple the risk of cardiovascular death in women of childbearing age.
    (4) Nearly all studies show a positive association between oral contraceptive use and cardiovascular disease.
    (5) The risk of cardiovascular disease increases soon after oral contraceptive use begins.

16 Match the causal criterion with its description. The names of the criteria are: (a) strength (b) consistency (c) specificity (d) temporality (e) biological gradient (f) plausibility (g) coherence (h) experimentation (i) analogy

Brief descriptions:
___ Requires that exposure precede onset of disease by a reasonable amount of time
___ Evidence from clinical trials, studies in test tubes, and studies in lab animals support the theory
___ Increases in the level, intensity, duration, or total amount of exposure leads to progressive increases in risk
___ Large associations provide firmer evidence of causality than do small ones 
___ Diverse methods of study carried out in different populations under a variety of circumstances by different investigators provide consistent results
___ The cause leads to only one disease and that the disease results from this single cause
___ Evidence "sticks together" as a whole 
___ Similarity in some respect with an otherwise different phenomenon. 
___ Association is based on established biological fact or theory.

Last update: 11/26/2007

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