3200: Introduction to Biostatistics inter 2018 omework #3 ritten Problems 1. Que

Question

3200: Introduction to Biostatistics inter 2018 omework #3 ritten Problems 1. Question 4.68 During the 1980s, approximately 22,000 physicians over the age of 40 agreed to participate in a long-term study called the Physicians' Health Study. One question investigated was whether aspirin helps lower the rate of heart attacks. The physicians were randomly assigned to take aspirin or to take a placebo. The physicians were then followed forward in time to see whether they had a heart attack a. Identify the response variable and the explanatory variable. b. Explain why this is an experiment and identify the treatments. c. Was this a retrospective or a prospective study? Explain. d. There are other explanatory variables, such as the amount of exercise a physician got, that we would expect to be associated with the response variable. Explain how such a variable is dealt with by the randomized nature of an experiment. Suppose the results of the study found that there was a lower rate of heart attacks in physicians who took aspirin compared to those who took the placebo. Does this prove that taking aspirin causes a reduction in the rate of heart attacks? Why or why not? e. uection 4 63 MacBook Air 2 F2 F4 F5 FT F8 F9

Explanation / Answer

Answer:

1).

a).

Response variable: had heart attack or not

Explanatory variable: drug( aspirin or placebo)

b). This is experiment because there is an intervention (taking the drug).

c).

This is prospective study because the physicians are followed over time.

d).

Randomization ensures that each physician has an equal chance of being placed in any group. This ensure that any differences between and within the groups are not systematic at the outset of the experiment.

e).

First drug was introduced and then physicians were followed. The effect followed by cause. yes, we may conclude that taking aspirin reduces the rate of heart rate.

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