Review Questions for Chapter 12

�12.1 Introduction

1. Name the two types of error in epidemiologic research.
2. How do parameters differ from estimators?
3. Describe the notational convention used by the text to distinguish parameters from estimators.
4. Provide a synonym for systematic error.
5. Provide a synonym for random error.
6. Provide an antonym for biased.
7. Provide an antonym for precise.
8. List ways in which random error differs from systematic error.

�12.2 Random Error 

1. [True or false?] Probability models are commonly used to adjust for bias in epidemiologic research. 
2. [T/F?] Objective and subjective views of probability are not compatible with each other. 
3. What two statistical procedures are used to address random error in epidemiologic studies?
4. Suppose the sample size an observation study could be expanded to infinitely large. What type of error would be eliminated. What type of error would not be eliminated?
5. [T/F?] Random error is expressed as the imprecision in an estimate.

�12.3 Systematic Error

1. Name three categories of bias in epi studies.
2. [True or false?] Nondifferential misclassification bias measures of effect away from the null.
3. [True or false?] A bias away from null tends to underestimate risks. 
4. Define confounding.
5. List the properties of a confounder.
6. What does the Latin word confundere mean?
7. Use of hospitalized controls in case-control studies could result in this type of bias.
8. Will a large study have less bias than a small study?
9. Subjects who experience an adverse outcome (cases) tend to give responses about potential causes of the adverse outcome that differ from those given by those that did not experience the outcome (non-cases). What type of bias can this cause?
10. What type of bias would occur if the code book for the data from an epidemiologic study was mixed up so that all exposed individuals were mistakenly identified as non-exposed, and vice-versa? 
11. In what situations will an extraneous risk factor not confound the association between an exposure and disease?
12. This question is from Rothman, 2002, p. 112. Those who favor representative studies claim that one cannot generalize a study to a population whose characteristics differ from those in the study population. Thus, a study of smoking and lung cancer in men would tell nothing about the relation between smoking and lung cancer in women. Give the counterarguments. (Clue:  If a study of smoking and lung cancer were conducted in London, would results apply to those who lived in Paris?)
13. In pharmacoepidemiologic studies, the term "confounding by indication" occurs when those who are given a certain drug have a different medical condition or severity of medical condition from those who did not take the drug. Is this truly a problem related to confounding, or is it better to classify this as a type of selection bias?

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