Project #18324 - Epidemiology

1). In a case control study of the association between chewing tobacco and oral cancer, you think that individuals with oral cancer are more likely to truthfully report that they chewed tobacco than controls.

 

a. What type of misclassification is this?  Be sure to state whether it is differential or nondifferential, AND whether it is misclassification of the exposure or the disease in your response. Justify your response. 

 

b. How would this misclassification bias the OR you calculate using your study findings? Be sure to state whether you think it would bias the OR toward or away from the null value of 1 in your response.  

 

2. An investigator conducted a cohort study to investigate the relationship between post-traumatic stress disorder (PTSD) and subsequent stroke.  The crude RR was 3.5, but after adjusting for frequent migraine headaches, the RR was 1.6.  Assuming you have determined that migraine headaches are NOT an effect modifier can you determine from these data results alone whether the headaches are a confounder or mediator? Why or why not?  Please describe what you need/must do to reach a conclusion.

 

 

3.  A case-control study of lung cancer and occupation was conducted among men living in Hyderabad, a city in India.  It identified excess risk of lung cancer among various occupations, including filling station attendants, bus drivers, and barbers.  (1) Define external validity (3 points) and (2) State whether or not there would be good external validity of these findings and be to provide several sentences to support your opinion . 

Subject Science
Due By (Pacific Time) 12/02/2013 12:00 pm
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