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Researchers wanted to test the effectiveness of a new cognitive behavioral therapy (CBT) compared with both an older behavioral treatment and a placebo therapy for treating insomnia. They identified 75 adults with insomnia. Patients were randomly assigned to one of three treatment groups. Twenty-five patients were randomly assigned to receive CBT (sleep education, stimulus control, and time-in-bed restrictions), another 25 received muscle relaxation training \((\mathrm{RT}),\) and the final 25 received a placebo treatment. Treatment lasted 6 weeks, with follow-up conducted at 6 months. To measure the effectiveness of the treatment, researchers used wake time after sleep onset (WASO). CBT produced larger improvements than did RT or placebo treatment. For example, the CBT-treated patients achieved an average \(54 \%\) reduction in their WASO, whereas RT-treated and placebo-treated patients, respectively, achieved only \(16 \%\) and \(12 \%\) reductions in this measure. Results suggest that CBT treatment leads to significant sleep improvements within 6 weeks, and these improvements appear to endure through 6 months of follow-up. (a) What type of experimental design is this? (b) What is the population being studied? (c) What is the response variable in this study? (d) What are the treatments? (e) Identify the experimental units. (f) Draw a diagram similar to Figure 7,8 , or 10 to illustrate the design.

Step by step solution

01

Identify the Type of Experimental Design

The experiment involves randomly assigning participants into multiple treatment groups to compare the effects of different treatments on a specific outcome. This is a randomized controlled trial (RCT).

02

Determine the Population Being Studied

The population being studied consists of adults with insomnia. The researchers targeted 75 adults who fit this criterion.

03

Identify the Response Variable

The response variable in this study is the wake time after sleep onset (WASO), which measures the effectiveness of the treatment.

04

List the Treatments

The treatments in this study are: (1) Cognitive Behavioral Therapy (CBT), (2) Muscle Relaxation Training (RT), and (3) a placebo treatment.

05

Identify the Experimental Units

The experimental units are the 75 adults with insomnia who participated in the study.

06

Illustrate the Design with a Diagram

To illustrate the design, create a diagram showing the 75 participants being randomly assigned into three groups, each group receiving one of the treatments, and tracking the response variable (WASO) over 6 weeks and at 6 months follow-up.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Experimental Design

Randomized Controlled Trials (RCTs) are used to test the effectiveness of treatments by randomly assigning participants to different groups. In this exercise, the researchers used an RCT to compare the effects of Cognitive Behavioral Therapy (CBT), muscle relaxation training (RT), and a placebo treatment on insomnia.
This design minimizes bias and helps ensure that differences in outcomes can be attributed to the treatments rather than other factors. By randomly assigning 75 adults with insomnia to one of three treatment groups, researchers ensured that each group had an equal chance of receiving any treatment. This helps create comparable groups and strengthens the validity of the results.

Wake Time After Sleep Onset (WASO)

Wake time after sleep onset (WASO) is the primary response variable in this study. It measures the time individuals spend awake after initially falling asleep.
WASO is a critical metric for evaluating insomnia treatments because it directly reflects sleep quality and continuity. A reduction in WASO indicates an improvement in sleep efficiency and overall restfulness. For this study, the effectiveness of each treatment was assessed by comparing the reductions in WASO among the groups.

• CBT group: 54% reduction in WASO
• RT group: 16% reduction in WASO
• Placebo group: 12% reduction in WASO

These results highlight that CBT was more effective in reducing WASO compared to RT and placebo treatments.

Cognitive Behavioral Therapy (CBT)

Cognitive Behavioral Therapy (CBT) is a structured and evidence-based approach that addresses dysfunctional thoughts and behaviors contributing to insomnia. It includes:

• Sleep education: Teaching patients about sleep hygiene and proper sleep practices.
• Stimulus control: Helping patients associate the bed and bedroom with sleep, and establishing a consistent sleep-wake schedule.
• Time-in-bed restrictions: Limiting the time spent in bed awake to increase sleep efficiency.

In this study, CBT proved to be the most effective treatment, achieving a 54% reduction in WASO. This suggests that CBT's comprehensive approach helps individuals improve their sleep patterns and maintain these improvements over time.

Muscle Relaxation Training (RT)

Muscle Relaxation Training (RT) is a behavioral technique used to reduce physical tension and promote relaxation. It often involves progressive muscle relaxation, where individuals tense and then slowly release different muscle groups.
In the context of insomnia treatment, RT aims to help individuals relax before bedtime, which can facilitate sleep onset and improve sleep quality. In this study, patients undergoing RT experienced a 16% reduction in WASO, indicating that while RT has some effectiveness, it is not as impactful as CBT.

Placebo Treatment

A placebo treatment is an inactive intervention used as a control to compare the effects of active treatments. It is crucial in RCTs to isolate the actual effects of the treatment from the psychological influence of receiving a treatment.
In this study, the placebo treatment group experienced a 12% reduction in WASO. This reduction may be attributed to the placebo effect, where patients experience real improvements due to their belief in the treatment's efficacy. While the placebo treatment shows some effect, it is clear from the results that active treatments like CBT and RT provide significantly greater improvements in sleep quality.