HW#3_ANSWER KEY - PH150a Homework#3 Randomized Control Trials Ecological Studies Ethics Please bring typed responses to your assigned Discussion

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PH150a Homework #3: Randomized Control Trials, Ecological Studies & Ethics Please bring typed responses to your assigned Discussion Section, February 11th-12th Learning Objectives: Review two common epidemiologic study designs Understand the concept of ecological fallacy Understand the importance of randomization Define: placebo, blinded, double-blinded, equipoise, and intention-to-treat Revisit critical ethical issues in human research Explore the realization of the above concepts in a primary research publication Fill in the rest of the table using your notes and slides from lecture: Ecological Study Randomized Controlled Trial Descriptive or Analytic? Analytic or Descriptive Analytic Timeframe for measurement of exposure/outcome Often outcome and exposure data have been collected previously; cross-sectional or retrospective analyses most common Goes forward in time, exposure measured before outcome occurs Observational or Experimental? Observational Experimental Study of… Individuals or Populations? Population (group) Individual or population (group) Advantages Quicker, inexpensive, easier; Previously collected data Similar advantages to prospective cohort, plus the ‘gold-standard’ for measuring causality. See question 6 Disadvantages Susceptible to the ecologic fallacy, results only apply to population level Can be long, expensive; not feasible for all situations (some exposures can’t be assigned, e.g. genes); can not ethically assign some exposures (e.g. smoking) Questions 1 through 4: The below study descriptions resemble partial abstracts from epidemiologic journal articles. For each, name the study design described and identify the key words, phrases or elements of the study that helped you determine the design. 1. Planned Caesarean Section versus Planned Vaginal Birth for Breech Presentation at Term We did a __________ to compare a policy of planned caesarean section with a policy of planned vaginal birth for selected breech-presentation pregnancies. At 131 centers in 22 countries, 3052 women with a singleton fetus in a breech presentation were randomly assigned planned caesarean section or planned vaginal birth. Mothers and infants were followed until 6 weeks post partum. The primary outcomes were infant mortality or serious neonatal morbidity. Analysis was by intention to treat.
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Answer: Randomized Controlled Trial – mothers were assigned either planned caesarean section or planned vaginal birth by the investigators; analysis was intention to treat. Outcomes occurred after the random assignment of exposures. 2. HPV and Risk of Oral Cancer
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This note was uploaded on 02/21/2010 for the course PH 150A taught by Professor Adams during the Spring '08 term at University of California, Berkeley.

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HW#3_ANSWER KEY - PH150a Homework#3 Randomized Control Trials Ecological Studies Ethics Please bring typed responses to your assigned Discussion

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