sample1 - Public Health 7-420 Clinical Trials Sample...

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Public Health 7-420 Clinical Trials Sample Mid-Quarter Examination Questions 1. What is a confounding variable? Give an example of one. Why is control of confounding variables in data analyses usually more important in observational compared to experimental studies? 2. Cite 3 benefits of randomization. 3. Distinguish between the types of "bias" that can be prevented by an appropriate randomization scheme and by blinding of treatments. 4. Cite an advantage of simple randomization. What is a possible implication of not achieving the desired allocation ratio as result of chance? 5. What is the purpose of permuted block randomization? Why are block sizes randomly mixed, particularly in non-blind studies? 6. In a survey of large cancer centers, 13/15 centers used a central telephone randomization scheme. Why do you think such a scheme was used? Discuss some alternatives. 7. A trial is planned of 1 st and 2 nd line treatments of treatments for glaucoma. Initially, patients will be randomized to receive medical treatment (i.e., drugs to reduce intra-ocular pressure) or surgical treatment (i.e., filtration surgery). Those who progress based on visual field testing will be randomly assigned to either laser treatment or to the alternative treatment from that initially assigned. The investigators are trying to decide when to randomize patients to the 2 nd line treatment, at the time of the initial randomization or at the time of progression. What do you advise?
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This note was uploaded on 11/21/2011 for the course PUBH 7420 taught by Professor Ph7420 during the Spring '07 term at Minnesota.

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sample1 - Public Health 7-420 Clinical Trials Sample...

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