Reference no: EM133618258
Indicate the one major type of limitation that is possible in each of the situations described below. Choose from the following: selection bias, information bias, confounding, random error, or limited generalizability.
1. An association between low fat margarine consumption and asthma was found in young adults. However, it was also found that overweight individuals tended to have a higher risk of asthma and to have different eating habits than those with normal weight
2. A survey of smoking among teenagers was conducted. The teens were asked if they ever smoked, if they still smoked, when they started and how often they smoked.
3. An epidemiologist examines the association between the use of diet pills and migraine headaches using a case-control study design. His participants are outpatients at a large community hospital. He finds that those using diet pills are more likely to complain of migraines, but he also discovers that those who have migraine headaches and use diet pills are more likely to be referred to the community hospital for outpatient diagnostic testing than those who have migraines but are not using diet pills.
4. The authors of a cross-sectional study hypothesized that lack of regular exercise is associated with obesity in children. Their study of 12 children in Michigan, however, failed to show a statistically significant association between exercise habits and obesity (PR = 1.9, p = 0.11).
5. In order to prevent confounding by gender and smoking status, a study of the relationship between exercise and heart attacks is conducted with a sample of men who do not smoke. Although confounding by these variables was prevented, another limitation was thereby introduced into the study. What was this limitation?
6. A negative association is found between bottle feeding and infant diarrhea in a third world country. In other words, contrary to expectations, breast fed infants were found to be more likely to develop diarrhea than bottle fed infants. This was a surprise because both the water and bottles were assumed to be vulnerable to contamination under poor living conditions. However, the investigators had failed to collect data on the education of the mothers. It was later discovered that more educated mothers were also more likely to bottle feed their infants. They also had more access to clean water.
7. A study to assess the association of diabetes and smoking compared a group of hospitalized individuals with diabetes (cases) with a group of volunteer individuals without diabetes (controls) who were full-time employees of the same hospital where the cases were identified. The results from this study reported, for the first time in the literature, a strong association between diabetes and smoking.