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Chapter 4: Q R4.9. (page 273)

An herb for depression? Does the herb Saint-John鈥檚-wort relieve major depression? Here is an excerpt from the report of a study on this issue: 鈥淒esign: Randomized, double-blind, placebo-controlled clinical trial.鈥�62 The study concluded that the herb is no more effective than a placebo.

(a) How did the design of this experiment account for the placebo effect?

(b) Why is a double-blind design a good idea in this setting?

Short Answer

Expert verified

Part (a) The placebo effect would occur if the drugs improved their condition.

Part (b) Researchers should also be blinded so they are unable to check out the influence.

Step by step solution

01

Part (a) Step 1: Given information

A placebo is more effective than an herb.

02

Part (a) Step 2: Concept

A placebo isan inactive treatment, sometimes called a 'sugar pill.

A placebo (false therapy) is given to a control group in several investigations. This reduces confusion caused by the placebo effect, in which some patients improve because they expect the treatment to work while receiving an inert treatment.

03

Part (a) Step 3: Explanation

A placebo has been said to be more effective than a herb.

If patients are given a medication that tastes and looks just like Saint John's wort, but it has no effect, it is considered a failure. Patients might believe they were being treated when, in fact, they were not. The placebo effect would occur if the drugs improved their condition.

04

Part (b) Step 1: Explanation

Both the researcher and the volunteers must remain unaware of the treatment they are receiving. Researchers should also be blinded in this case to prevent them from detecting the influence.

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