Indicate the one major type of limitation that is possible in each of the situat
ID: 3309776 • Letter: I
Question
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 no error.
Choose only one per example.
1) A case-control study was conducted to assess the association of passive smoking and asthma. Newly diagnosed asthmatic individuals (cases) and a random sample of individuals without asthma symptoms (controls) were questioned in regard to exposure to second hand smoke at home or in the workplace throughout their lives.
2) A cross-sectional survey is conducted by randomly visiting homes in residential areas to determine the prevalence of Alzheimer’s disease.
3) 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).
4) A study of the relationship between contact lens use and the risk of eye ulcers is conducted. The crude relative risk was 3.0. The investigators had failed to adjust for age, which would have yielded a relative risk of 1.5.
Explanation / Answer
1) Information Bias
Here individuals are asked to recall about their exposure throughout their life. There may be the case they fail to recall which will lead to information bias.
2)
Random error
3)
Selection Bias
Here the sample size chosen is very small that could lead to selection bias
4)
Confounding
Due to the factor of age the parameter value has reduced hence this is the case of confounding