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Chapter 4: Q. 88 (page 268)

A report in a medical journal notes that the risk of developing Alzheimer鈥檚 disease among subjects who regularly opted to take the drug ibuprofen was about half the risk of those who did not. Is this good evidence that ibuprofen is effective in preventing Alzheimer鈥檚 disease?

a. Yes, because the study was a randomized, comparative experiment.

b. No, because the effect of ibuprofen is confounded with the placebo effect.

c. Yes, because the results were published in a reputable professional journal.

d. No, because this is an observational study. An experiment would be needed to confirm

(or not confirm) the observed effect.

e. Yes, because a 50%reduction can鈥檛 happen just by chance.

Short Answer

Expert verified

Option d is correct: No, because this is an observational study. An experiment would be needed to confirm

(or not confirm) the observed effect.

Step by step solution

01

Given Information

We are given a report of medical journal that the risk of developing Alzheimer鈥檚 disease among subjects who regularly opted to take the drug ibuprofen was about half the risk of those who did not.

We need to find out whether is this good evidence that ibuprofen is effective in preventing Alzheimer鈥檚 disease and select correct answer from given option.

02

Explanation

Because this is an observational study, the answer is no. To validate (or disprove) the observed effect, an experiment would be required. The reason for this is because, whereas experiments can prove cause and effect when done correctly, observational studies can't since there are much too many variables. In observational research, only a correlation between the explanatory and response variables may be shown. As a result, option d is correct option.

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Most popular questions from this chapter

Cocoa and blood flow A study of blood flow involved 27healthy people aged 18to 72. Each subject consumed a cocoa beverage containing 900milligrams of flavonols daily for 5days. Using a finger cuff, blood flow was measured on the first and fifth days of the study. After 5 days, researchers measured what they called 鈥渟ignificant improvement鈥� in blood flow and the function of the cells that line the blood vessels. What flaw in the design of this experiment makes it impossible to say if the cocoa really caused the improved blood flow? Explain your answer.

How is your room? A hotel has 30floors with 40rooms per floor. The rooms on one side of the hotel face the water, while rooms on the other side face a golf course. There is an extra charge for the rooms with a water view. The hotel manager wants to select 120rooms and survey the registered guest in each of the selected rooms about his or her overall satisfaction with the property.

a. Describe how to obtain a sample of 120rooms using stratified random sampling. Explain your choice of strata and why this method might be preferred to simple random sampling.

b. Describe how to obtain a sample of 120rooms using cluster sampling. Explain your choice of clusters and why this method might be preferred to simple random sampling.

Wording bias Comment on each of the following as a potential sample survey question.

Is the question clear? Is it slanted toward a desired response?

a. 鈥淪ome cell phone users have developed brain cancer. Should all cell phones come with

a warning label explaining the danger of using cell phones?鈥�

b. 鈥淒o you agree that a national system of health insurance should be favored because it

would provide health insurance for everyone and would reduce administrative costs?鈥�

c. 鈥淚n view of escalating environmental degradation and incipient resource depletion,

would you favor economic incentives for recycling of resource鈥搃ntensive consumer

驳辞辞诲蝉?鈥�

Consider an experiment to investigate the effectiveness of different insecticides in

controlling pests and their impact on the productivity of tomato plants. What is the best

reason for randomly assigning treatment levels (spraying or not spraying) to the

experimental units (farms)?

a. Random assignment eliminates the effects of other variables, like soil fertility.

b. Random assignment eliminates chance variation in the responses.

c. Random assignment allows researchers to generalize conclusions about the

effectiveness of the insecticides to all farms.

d. Random assignment will tend to average out all other uncontrolled factors such as

soil fertility so that they are not confounded with the treatment effects.

e. Random assignment helps avoid bias due to the placebo effect.

A simple random sample of 1200 adult Americans is selected, and each person is asked

the following question: 鈥淚n light of the huge national deficit, should the government at this

time spend additional money to send humans to Mars?鈥� Only 39% of those responding

answered 鈥淵es.鈥� This survey

a. is reasonably accurate because it used a large simple random sample.

b. needs to be larger because only about 24 people were drawn from each state.

c. probably understates the percent of people who favor sending humans to Mars.

d. is very inaccurate but neither understates nor overstates the percent of people who favor

sending humans to Mars. Because simple random sampling was used, it is unbiased.

e. probably overstates the percent of people who favor sending humans to Mars.
See all solutions

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