QUESTION 1: A study used self-administered mail questionnaires to gather data on height and weight in order to calculate a measure of obesity. Which of the following types of problems were likely avoided by this method of data collection, and why?
- Interviewer bias
- Exposure misclassification
- Confounding
- Selection bias
- Loss-to-follow-up
QUESTION 2: A case-control study was performed to determine whether head injury was associated with an increased risk of brain tumors in children. 200 cases with brain cancer were identified from the state cancer registry and 200 controls were recruited from the same neighborhoods where the cases lived. The mothers of the children completed a questionnaire that asked them to describe their child's past history of head injury. The investigators found that the mothers of the children with brain tumors reported a past head injury for 70 of the cases while a past history of head injury was reported in 30 of the controls. What type of bias was likely to have influenced the findings of this study, and why? What can be done to minimize this type of bias?
QUESTION 3: Name four types of information bias. Name at least one way in which each type of bias can be prevented or minimized.