A study is funded by the tobacco industry to examine the association between smoking and lung cancer. They design a study with a prospective cohort of 1,000 smokers between the ages of 20-30. The length of the study is five years. After the study period ends, they conclude that there is no relationship between smoking and lung cancer. Which of the following study features is the most likely reason for the failure of the study to note an association between tobacco use and cancer?
ALate-look bias
BLatency period
CConfounding
DEffect modification
EPygmalion effect
You have been asked to quantify the relative risk of developing bacterial meningitis following exposure to a patient with active disease. You analyze 200 patients in total, half of which are controls. In the trial arm, 30% of exposed patients ultimately contracted bacterial meningitis. In the unexposed group, only 1% contracted the disease. Which of the following is the relative risk due to disease exposure?
A(30 * 99) / (70 * 1)
B[30 / (30 + 70)] / [1 / (1 + 99)]
C[70 / (30 + 70)] / [99 / (1 + 99)]
D[[1 / (1 + 99)] / [30 / (30 + 70)]]
E(70 * 1) / (30 * 99)
You are reviewing the protocol for a retrospective case-control study investigating risk factors for mesothelioma among retired factory workers. 100 cases of mesothelioma and 100 age and sex matched controls are to be recruited and interviewed about their exposure to industrial grade fiberglass by blinded interviewers. The investigators' primary hypothesis is that cases of mesothelioma will be more likely to have been exposed to industrial grade fiberglass. The design of this study is most concerning for which type of bias?
AThis study design is free of potential bias
BObserver bias
CInterviewer bias
DLead-time bias
ERecall bias
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