Does the herb St. John’s wort relieve major depression? Here is an excerpt from the report of one study of this issue: “Design: Randomized, Double-Blind, Placebo-Controlled Clinical Trial.” The study concluded that the difference in effectiveness of St. John’s wort and a placebo was not statistically significant.

a. Describe the placebo effect in this context. How did the design of this experiment account for the placebo effect?

b. Explain the purpose of the random assignment.

c. Why is a double-blind design a good idea in this setting?

d. Explain what “not statistically significant” means in this context

Short Answer

Expert verified

a. As, it gave some patients a pill that should have no effect at all but looks, tastes, and feels like the Saint-John’s-wort. These people think that they are being treated, but in fact, they are not. So if they get better, this would be a case of the placebo effect.

b. The purpose of this random assignment was to create two groups of subjects that are about the same in the beginning of the experiment. As this reduces bias in the conducting of the experiment.

c. Double-blind is when neither the patient or experimenter know what treatment is given. The subject should not know which treatment they are receiving so that the researchers can measure how much placebo effect there is. But the researchers should also be blinded so that they cannot influence how they measure the results.

d. “Not statistically significant” means in this context that the difference in improvement between the two groups was not large enough to rule out potential chance variation resulting for random assignment of the variables.

Step by step solution

01

Part a. Step 1. Explanation

As, it gave some patients a pill that should have no effect at all but looks, tastes, and feels like the Saint-John’s-wort. These people think that they are being treated, but in fact, they are not. So if they get better, this would be a case of the placebo effect.

02

Part b. Step 1. Explanation

The purpose of this random assignment was to create two groups of subjects that are about the same in the beginning of the experiment. As this reduces bias in the conducting of the experiment.

03

Part c. Step 1. Explanation

Double-blind is when neither the patient or experimenter know what treatment is given. The subject should not know which treatment they are receiving so that the researchers can measure how much placebo effect there is. But the researchers should also be blinded so that they cannot influence how they measure the results.

04

Part d. Step 1. Explanation

“Not statistically significant” means in this context that the difference in improvement between the two groups was not large enough to rule out potential chance variation resulting for random assignment of the variables.

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Most popular questions from this chapter

More testosterone Refer to Exercise 56. Could blinding be used in this experiment? Explain your reasoning. Why is blinding an important consideration in this context?

Your statistics class has 30students. You want to ask an SRS of 5students from your class whether they use a mobile device for the online quizzes. You label the students 01,02,...,30. You enter the table of random digits at this line: 1445926056314248037165103622532249061181

Your SRS contains the students labeled

a. 14,45,92,60,56

b. 14,31,03,10,22

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

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A louse-y situation A study published in the New England Journal of Medicine compared two medicines to treat head lice: an oral medication called ivermectin and a topical lotion containing malathion. Researchers studied 812 people in 376 households in seven areas around the world. Of the 185 households randomly assigned to ivermectin, 171 were free from head lice after 2 weeks, compared with only 151 of the 191 households randomly assigned to malathion.

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