/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 46 An experiment to evaluate whethe... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 2: Problem 46

An experiment to evaluate whether vitamins can help prevent recurrence of blocked arteries in patients who have had surgery to clear blocked arteries was described in the article "Vitamins Found to Help Prevent Blocked Arteries" (Associated Press, September 1, 2002). The study involved 205 patients who were given either a treatment consisting of a combination of folic acid, vitamin B 12, and vitamin B6 or a placebo for 6 months. a. Explain why a placebo group was used in this experiment. b. Explain why it would be important for the researchers to have assigned the 205 subjects to the two groups (vitamin and placebo) at random. c. Do you think it is appropriate to generalize the results of this experiment to the population of all patients who have undergone surgery to clear blocked arteries? Explain.

Short Answer

Expert verified
a. A placebo group was used in the experiment to serve as a control group and to isolate the therapeutic effects of the vitamins treatment. b. Random assignment to the two groups was important to eliminate any systematic bias and to ensure that any difference in the outcome was due to the treatment only. c. When it comes to generalization, it requires careful consideration of the sample size and the demographics of the sampled patients. This is because for valid generalization, the sample should be representative of the entire population.

Step by step solution

01

Understanding the usage of placebo

A placebo group is used in an experiment to serve as a control group. Placebo is a substance with no therapeutic effect and is provided to patients in the control group. This is to check whether the observed effects in the experiment are due to the vitamins treatment or due to other factors including psychological effects like placebo effect where the patient feels better because they think they are getting treatment.
02

Understanding random assignment

Random assignment of the subjects to the different groups is important to eliminate any systematic bias. It ensures that any other effect except the treatment would be evenly distributed among the two groups, thus any difference in the outcome would be due to the treatment only.
03

Assessing generalization of results

To generalize the results of the experiment to the entire population of all patients who have undergone surgery to clear blocked arteries would require careful consideration of the sample size used in the experiment and the demographic similarities between the sample and the wider population. In this case, the study only consists of 205 patients. For a more reliable generalisation, the study should be replicated with larger and more diverse samples to ensure it is representative of the entire population.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Explain why blinding is a reasonable strategy in many experiments.

Suppose that you were asked to help design a survey of adult city residents in order to estimate the proportion that would support a sales tax increase. The plan is to use a stratified random sample, and three stratification schemes have been proposed. Scheme 1: Stratify adult residents into four strata based on the first letter of their last name (A-G, \(\mathrm{H}-\mathrm{N}, \mathrm{O}-\mathrm{T}, \mathrm{U}-\mathrm{Z})\) Scheme 2: Stratify adult residents into three strata: college students, nonstudents who work full time, nonstudents who do not work full time. Scheme 3: Stratify adult residents into five strata by randomly assigning residents into one of the five strata. Which of the three stratification schemes would be best in this situation? Explain.

For each of the situations described, state whether the sampling procedure is simple random sampling, stratified random sampling, cluster sampling, systematic sampling, or convenience sampling. a. All freshmen at a university are enrolled in 1 of 30 sections of a seminar course. To select a sample of freshmen at this university, a researcher selects 4 sections of the seminar course at random from the 30 sections and all students in the 4 selected sections are included in the sample. b. To obtain a sample of students, faculty, and staff at a university, a researcher randomly selects 50 faculty members from a list of faculty, 100 students from a list of students, and 30 staff members from a list of staff. c. A university researcher obtains a sample of students at his university by using the 85 students enrolled in his Psychology 101 class. d. To obtain a sample of the seniors at a particular high school, a researcher writes the name of each senior on a slip of paper, places the slips in a box and mixes them, and then selects 10 slips. The students whose names are on the selected slips of paper are included in the sample. e. To obtain a sample of those attending a basketball game, a researcher selects the 24 th person through the door. Then, every 50 th person after that is also included in the sample.

A mortgage lender routinely places advertisements in a local newspaper. The advertisements are of three different types: one focusing on low interest rates, one featuring low fees for first-time buyers, and one appealing to people who may want to refinance their homes. The lender would like to determine which advertisement format is most successful in attracting customers to call for more information. Describe an experiment that would provide the information needed to make this determination. Be sure to consider extraneous factors, such as the day of the week that the advertisement appears in the paper, the section of the paper in which the advertisement appears, or daily fluctuations in the interest rate. What role does randomization play in your design?

Researchers at the University of Houston decided to test the hypothesis that restaurant servers who squat to the level of their customers would receive a larger tip ("Effect of Server Posture on Restaurant Tipping," Journal of Applied Social Psychology [1993]: \(678-685\) ). In the experiment, the waiter would flip a coin to determine whether he would stand or squat next to the table. The waiter would record the amount of the bill and of the tip and whether he stood or squatted. a. Describe the treatments and the response variable. b. Discuss possible extraneous factors and how they could be controlled. c. Discuss whether blocking would be necessary. d. Identify possible confounding variables. e. Discuss the role of randomization in this experiment.
See all solutions

Recommended explanations on Math Textbooks

Decision Maths

Read Explanation

Geometry

Read Explanation

Discrete Mathematics

Read Explanation

Applied Mathematics

Read Explanation

Mechanics Maths

Read Explanation

Calculus

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.