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Testing the placebo effect. The placebo effect describes
Chapter 7, Problem 144SE(choose chapter or problem)
Problem 144SE
Testing the placebo effect. The placebo effect describes the phenomenon of improvement in the condition of a patient taking a placebo—a pill that looks and tastes real but contains no medically active chemicals. Physicians at a clinic in La Jolla, California, gave what they thought were drugs to 7,000 asthma, ulcer, and herpes patients. Although the doctors later learned that the drugs were really placebos, 70% of the patients reported an improved condition. Use this information to test (at = .05) the placebo effect at the clinic. Assume that if the placebo is ineffective, the probability of a patient’s condition improving is .5.
Questions & Answers
QUESTION:
Problem 144SE
Testing the placebo effect. The placebo effect describes the phenomenon of improvement in the condition of a patient taking a placebo—a pill that looks and tastes real but contains no medically active chemicals. Physicians at a clinic in La Jolla, California, gave what they thought were drugs to 7,000 asthma, ulcer, and herpes patients. Although the doctors later learned that the drugs were really placebos, 70% of the patients reported an improved condition. Use this information to test (at = .05) the placebo effect at the clinic. Assume that if the placebo is ineffective, the probability of a patient’s condition improving is .5.
ANSWER:
Solution :
Step 1 of 1:
Given physicians at a clinic in La Jolla, California, gave what they thought were drugs to 7000 asthma, ulcer, and patient.
Then the probability of a patient's condition improving is 0.5.
Here the proportion of patients taking the pill who reported an improved condition.
Now we have to check normal approximation is adequate.
Now we have to find and
.
We know that n=7000 and .
Then, is
Where .