Book: Epidemiology An Introduction
Author: Kenneth J. Rothman

3) Answer question 6 of chapter 4 in Rothman?s book.
If a person has already been selected as a control in a case-control
study and then later during the study period develops the disease
being studied, should the person be kept in the study as (1) a case,
(2) a control,(3) both, or (4) neither?

4) Answer question 5 of chapter 5 in RB.
Explain the difference between a confounding factor and a potential
confounding factor. In what situations might a potential confounding
factor not end up being a confounding factor?

6) Answer question 7 of chapter 6 in RB.
Are confidence intervals always symmetrical around the point estimate?
Why or why not?

7) Answer question 3 of chapter 9 in RB.
In an analysis of the effect of oral contraceptives on stroke based on
the data in Table 9-2, suppose that you were interested in the oral
contraceptive effect and wished only to control for possible
confounding by hypertension using stratification. What would be the
stratum-specific risk ratio estimates for oral-contraceptive use for
two strata of hypertension? In an ordinary stratified analysis, why is
there a separate referent category in each stratum?