Ch. 1 - Introduction to Statistics

Larson - Elementary Statistics: Picturing the World 8th Edition

Larson8th EditionElementary Statistics: Picturing the WorldISBN: 9780137493470Not the one you use?Change textbook

Larson 8th Edition

Ch. 1 - Introduction to Statistics

Problem 1.3.20b

Chapter 1, Problem 1.3.20b

"Researchers in Japan tested the effect of cannabidiol (CBD) in treating late teenagers with social anxiety disorder (SAD). Thirty-seven 18- to 19-year-old teenagers with SAD took part in the study. The patients were assigned at random to receive a daily dose of either CBD or a placebo for 4 weeks. Symptoms were measured using The Fear of Negative Evaluation Questionnaire and the Liebowitz Social Anxiety Scale at the beginning and end of the treatment. (Source: Frontiers in Psychology)
Identify a potential problem with the experimental design being used and suggest a way to improve it."

Verified step by step guidance

Identify the key components of the experimental design: The study involves two groups (CBD and placebo), random assignment, and measurement of symptoms using two scales before and after treatment.

Recognize a potential problem: The study does not mention whether the researchers or participants were blinded to the treatment condition. Lack of blinding can introduce bias, as participants' or researchers' expectations might influence the results.

Explain why blinding is important: Blinding ensures that neither the participants nor the researchers know who is receiving the treatment or placebo, reducing the risk of bias and ensuring that the observed effects are due to the treatment itself.

Suggest an improvement: Implement a double-blind design where both the participants and the researchers administering the treatment are unaware of who is receiving CBD and who is receiving the placebo.

Highlight the benefit of the improvement: A double-blind design would enhance the validity of the study by minimizing bias and ensuring that the results are more reliable and attributable to the treatment effect.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Randomization

Randomization is a fundamental principle in experimental design that involves randomly assigning participants to different treatment groups. This process helps to eliminate selection bias, ensuring that each group is comparable at the start of the experiment. In the context of the study, randomization is crucial for attributing any observed effects of CBD on social anxiety disorder to the treatment itself rather than to pre-existing differences between participants.

Placebo Effect

The placebo effect occurs when participants experience a perceived improvement in their condition simply because they believe they are receiving treatment, even if it is a placebo. This phenomenon can confound the results of clinical trials, making it difficult to determine the true efficacy of the treatment. In the study, ensuring that both the CBD and placebo groups are treated identically, except for the active ingredient, is essential to accurately assess the impact of CBD on social anxiety.

Measurement Validity

Measurement validity refers to the extent to which a tool or instrument accurately measures what it is intended to measure. In this study, the use of The Fear of Negative Evaluation Questionnaire and the Liebowitz Social Anxiety Scale is critical for assessing the symptoms of social anxiety disorder. Ensuring that these measures are valid and reliable is essential for drawing meaningful conclusions about the effectiveness of CBD in treating SAD among the participants.

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Textbook Question

A company wants to test the effectiveness of a new acne cream. The company recruits 500 girls ages 13 to 17 who have acne. The subjects are randomly assigned into two groups. One group is given the acne cream and the other is given a placebo that looks exactly like the acne cream. Both groups apply the cream daily for two months. Facial photos are taken at the beginning and end of the treatment to compare results.

b. Identify a potential problem with the experimental design being used and suggest a way to improve it.

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Textbook Question

Identify the experimental units and treatments used in this experiment.

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Textbook Question

"Researchers in Japan tested the effect of cannabidiol (CBD) in treating late teenagers with social anxiety disorder (SAD). Thirty-seven 18- to 19-year-old teenagers with SAD took part in the study. The patients were assigned at random to receive a daily dose of either CBD or a placebo for 4 weeks. Symptoms were measured using The Fear of Negative Evaluation Questionnaire and the Liebowitz Social Anxiety Scale at the beginning and end of the treatment. (Source: Frontiers in Psychology)

The experiment is described as a placebo-controlled, double-blind study. Explain what this means."

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Textbook Question

Researchers in Japan tested the effect of cannabidiol (CBD) in treating late teenagers with social anxiety disorder (SAD). Thirty-seven 18- to 19-year-old teenagers with SAD took part in the study. The patients were assigned at random to receive a daily dose of either CBD or a placebo for 4 weeks. Symptoms were measured using The Fear of Negative Evaluation Questionnaire and the Liebowitz Social Anxiety Scale at the beginning and end of the treatment. (Source: Frontiers in Psychology)

a. Identify the experimental units and treatments used in this experiment.

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Textbook Question

Identify the sampling technique used, and discuss potential sources of bias (if any). Explain.

Questioning teachers as they leave a faculty lounge, a researcher asks 45 of them about their teaching styles.

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Textbook Question

c. How could this experiment be designed to be double-blind?

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