In 1990, a case-control study was conducted to investigate the positive association between artificial sweetener use and bladder cancer. Controls were selected from a hospital sample of patients diagnosed with obesity-related conditions. Obesity-related conditions have been positively associated with artificial sweetener use. How would the use of these patients as controls affect the estimate of the association between artificial sweetener use and bladder cancer?
a. The estimate of association would accurately reflect the true association regardless of the association between artificial sweetener use and obesity-related conditions
b. The estimate of association would tend to underestimate the true association
c. More information is needed on the strength of association between artificial sweetener use and obesity-related conditions before any judgment can be made
d. The estimate of association would tend to overestimate the true association
e. More information is needed on the strength of association between artificial sweetener use and bladder cancer before any judgment can be made
Answer: b. The estimate of association would tend to underestimate the true association