1. Intro to Stats and Collecting Data

Intro to Stats

1. Intro to Stats and Collecting Data

Intro to Stats

3:43 minutes

Problem 1.T.19c

Textbook Question

Nucryst Pharmaceuticals, Inc., announced the results of its first human trial of NPI 32101, a topical form of its skin ointment. A total of 225 patients diagnosed with skin irritations were randomly divided into three groups as part of a double-blind, placebo-controlled study to test the effectiveness of the new topical cream. The first group received a 0.5% cream, the second group received a 1.0% cream, and the third group received a placebo. Groups were treated twice daily for a 6-week period.

c. What does it mean for this study to be double-blind?

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Understand that a double-blind study is a type of experimental design used to prevent bias in research results.

In a double-blind study, neither the participants (patients) nor the researchers administering the treatment know which group is receiving the active treatment or the placebo.

This means that the patients do not know if they are receiving the 0.5% cream, the 1.0% cream, or the placebo, which helps prevent their expectations from influencing the outcome.

Similarly, the researchers who interact with the patients or assess the results do not know which treatment each patient received, which helps prevent their observations or behavior from biasing the results.

Overall, the double-blind design helps ensure that the study's findings about the effectiveness of the topical cream are more reliable and valid by minimizing both participant and experimenter bias.

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Key Concepts

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

Double-Blind Study

A double-blind study is a research design where neither the participants nor the researchers know who is receiving the treatment or the placebo. This approach minimizes bias in treatment administration and outcome assessment, ensuring that expectations do not influence the results.

Placebo-Controlled Study

A placebo-controlled study includes a group receiving an inactive substance (placebo) to compare against groups receiving the actual treatment. This helps determine if the treatment's effects are due to the active ingredient or psychological factors like the placebo effect.

Randomization

Randomization is the process of assigning participants to different groups by chance, reducing selection bias. It ensures that each group is comparable at the start, allowing for a fair assessment of the treatment's effectiveness.

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Each of the following surveys has bias. Identify the type of bias.

A researcher conducting a poll about national politics sends a survey to a random sample of subscribers to Time magazine.

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Who are the subjects?

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Textbook Question

What is the response variable? Is it qualitative or quantitative?

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e. Explain the role randomization plays in this experiment.

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Insomnia 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 (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. 53 Source: Jack D. Edinger, PhD; William K. Wohlgemuth, PhD; Rodney A. Radtke, MD; Gail R. Marsh, PhD; Ruth E. Quillian, PhD. “Cognitive Behavioral Therapy for Treatment of Chronic Primary Insomnia,” Journal of the American Medical Association 285: 1856–1864, 2001

What is the population being studied?

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What is the response variable in this study?

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The Memory Drug? Researchers wanted to evaluate whether ginkgo, an over-the-counter herb marketed as enhancing memory, improves memory in elderly adults as measured by objective tests. To do this, they recruited 98 men and 132 women older than 60 years and in good health. Participants were randomly assigned to receive ginkgo, 40 milligrams (mg) 3 times per day, or a matching placebo. The measure of memory improvement was determined by a standardized test of learning and memory. After 6 weeks of treatment, the data indicated that ginkgo did not increase performance on standard tests of learning, memory, attention, and concentration. These data suggest that, when taken following the manufacturer’s instructions, ginkgo provides no measurable increase in memory or related cognitive function to adults with healthy cognitive function.

What is the factor that is set to predetermined levels? What are the treatments?

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What type of experimental design is this?

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