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Chapter 1: Problem 2

Consider a completely randomized experiment in which a control group is given a placebo for congestion relief and a treatment group is given a new drug for congestion relief. Describe a double-blind procedure for this experiment and discuss some benefits of such a procedure.

Short Answer

Expert verified
In a double-blind study, neither participants nor researchers know who receives the treatment or placebo, reducing bias and increasing the reliability of results.

Step by step solution

01

Understand the Objective

The goal is to compare the efficacy of a placebo against a new drug for congestion relief in a double-blind study. 'Double-blind' means that neither the participants nor the researchers know who receives the treatment or the placebo.
02

Setup of the Double-Blind Procedure

In a double-blind procedure, randomly assign participants into two groups: the treatment group and the control group. Prepare the treatment drug and a placebo to look identical. Label them such that the labels do not reveal the contents.
03

Maintain Blinding During the Experiment

The doctors administering the drugs and the participants both should be unaware of which group is receiving the treatment versus the placebo. This ensures that the administration of the drug is unbiased and the expectations do not influence the results.
04

Collection and Analysis of Data

Collect data on congestion relief from both groups. Since neither the participants nor the administrators know who took the drug and who took the placebo, any observed difference can more likely be attributed to the effect of the drug itself rather than placebo effects or biases.
05

Benefits of Double-Blind Procedure

This procedure reduces biases, such as the placebo effect and observer bias. It ensures that neither participants' nor researchers' expectations influence the outcomes, leading to more reliable results.

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Key Concepts

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

Control Group
When conducting scientific experiments, a control group plays a pivotal role. It serves as a standard of comparison to the experimental or treatment group.

In the context of a double-blind experiment, the control group is given a placebo 鈥� an inactive substance designed to have no therapeutic value. This is crucial because it allows researchers to determine if changes in the experimental group are actually due to the treatment itself, and not some other factor.
  • Standardization: Both the control and treatment groups must be treated equally in every possible way except for the intervention being tested.
  • Randomization: Participants are randomly assigned to either the control or treatment group to ensure that results are valid and not skewed by selection bias.
  • Measurement: Without a proper control group, it's challenging to measure the true effectiveness of the intervention.
By using a control group, researchers can clarify the difference between the actual impact of the drug and the naturally occurring changes, improving the validity of the experiment's findings.
Placebo Effect
The placebo effect is a fascinating and often bewildering phenomenon where patients experience real changes in their symptoms despite having received an inactive treatment.

In a double-blind experiment, this effect can occur because participants believe they are receiving real medication. This belief can trigger psychological and physiological responses similar to those produced by the actual drug.
  • Expectation: Even if the pill is inert, hope and expectation can lead to symptom improvement.
  • Pain Reduction: Studies have shown the placebo effect can lead to actual reductions in pain perception.
  • Physiological Response: Placebo can cause measurable changes in brain activity, illustrating the power of belief on the body.
Understanding the placebo effect helps researchers analyze whether the drug provides benefits beyond psychological assurances, ensuring that the effects measured are due to the treatment itself.
Experimental Design
Crafting a robust experimental design is the cornerstone of effective scientific inquiry. It ensures that the experiment can accurately test the hypothesis or research question.

When designing an experiment, especially a double-blind one, several elements must be considered to uphold the integrity of the study鈥檚 findings.
  • Double-Blind Setup: Ensure that neither the participants nor the experimenters know which subjects are in the treatment group or control group. This prevents bias.
  • Randomization: Assign subjects to groups randomly to distribute any other confounding variables evenly.
  • Consistency: Keeping all conditions the same for the control and treatment groups, excluding the one variable being tested, allows for clearer interpretation of results.
These aspects of experimental design ensure that the findings are credible and can ultimately be replicated in future research. It is through this meticulous planning that scientific studies maintain their reliability and validity.

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Most popular questions from this chapter

How would you use a completely randomized experiment in each of the following settings? Is a placebo being used or not? Be specific and give details. (a) A veterinarian wants to test a strain of antibiotic on calves to determine their resistance to common infection. In a pasture are 22 newborn calves. There is cnough vaccine for 10 calves. However, blood tests to determine resistance to infection can be done on all calves. (b) The Denver Police Department wants to improve its image with teenagers. \(\mathrm{A}\) uniformed officer is sent to a school one day a week for 10 weeks. Each day the officer visits with students, eats lunch with students, attends pep rallies, and so on. There are 18 schools, but the police department can visit only half of these schools this semester. A survey regarding how teenagers view police is sent to all 18 schools at the end of the semester. (c) A skin patch contains a new drug to help people quit smoking. A group of 75 cigarette smokers have volunteered as subjects to test the new skin patch. For one month, 40 of the volunteers receive skin patches with the new drug. The other volunteers receive skin patches with no drugs. At the end of two months, each subject is surveyed regarding his or her current smoking habits.

Die A die is a cube with dots on each face. The faces have \(1,2,3,4,5\), or 6 dots. The table below is a computer simulation (from the software package Minitab) of the results of rolling a fair die 20 times. $$ \begin{aligned} &\text { DATA DISPLAY }\\\ &\begin{array}{c|cccccccccc} \text { ROW } & \text { C1 } & \text { C2 } & \text { C3 } & \text { C4 } & \text { C5 } & \text { C6 } & \text { C7 } & \text { C8 } & \text { C9 } & \text { C10 } \\ \hline 1 & 5 & 2 & 2 & 2 & 5 & 3 & 2 & 3 & 1 & 4 \\ 2 & 3 & 2 & 4 & 5 & 4 & 5 & 3 & 5 & 3 & 4 \end{array} \end{aligned} $$ (a) Assume that each number in the table corresponds to the number of dots on the upward face of the die. Is it appropriate that the same number appears more than once? Why? What is the outcome of the fourth roll? (b) If we simulate more rolls of the die, do you expect to get the same sequence of outcomes? Why or why not?

Modern Managed Hospitals (MMH) is a national for-profit chain of hospitals. Management wants to survey patients discharged this past year to obtain patient satisfaction profiles. They wish to use a sample of such patients. Several sampling techniques are described below. Categorize each technique as simple random sample, stratified sample, systematic sample, cluster sample, or convenience sample. (a) Obtain a list of patients discharged from all MMH facilities. Divide the patients according to length of hospital stay \((2\) days or less, \(3-7\) days, \(8-14\) days, more than 14 days). Draw simple random samples from each group. (b) Obtain lists of patients discharged from all MMH facilities. Number these patients, and then use a random-number table to obtain the sample. (c) Randomly select some MMH facilitics from each of five geographic regions, and then include all the patients on the discharge lists of the selected hospitals. (d) At the beginning of the year, instruct each MMH facility to survey every 500th patient discharged. (e) Instruct each MMH facility to survey 10 discharged patients this week and send in the results.

Use a random-number table to simulate the outcomes of tossing a quarter 25 times. Assume that the quarter is balanced (i.e., fair).

Use a random-number table to generate a list of eight random numbers from 1 to \(976 .\) Explain your work.
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