/*! 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 21 Exercise and mental health. A re... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 1: Problem 21

Exercise and mental health. A researcher is interested in the effects of exercise on mental health and he proposes the following study: Use stratified random sampling to ensure representative proportions of \(18-30,31-40\) and \(41-55\) year olds from the population. Next, randomly assign half the subjects from each age group to exercise twice a week, and instruct the rest not to exercise. Conduct a mental health exam at the beginning and at the end of the study, and compare the results. (a) What type of study is this? (b) What are the treatment and control groups in this study? (c) Does this study make use of blocking? If so, what is the blocking variable? (d) Does this study make use of blinding? (e) Comment on whether or not the results of the study can be used to establish a causal relationship between exercise and mental health, and indicate whether or not the conclusions can be generalized to the population at large. (f) Suppose you are given the task of determining if this proposed study should get funding. Would you have any reservations about the study proposal?

Short Answer

Expert verified
(a) Randomized controlled trial; (b) Exercise group, Non-exercise group; (c) Yes, age group; (d) No; (e) Yes for causality, limited for generalization; (f) Consider confounders and study duration.

Step by step solution

01

Identify Study Type

The study is a randomized controlled trial (RCT). RCTs are characterized by the random assignment of participants into different groups to test the effect of a variable while minimizing bias.
02

Determine Treatment and Control Groups

In this study, the treatment group consists of those who are assigned to exercise twice a week. The control group is composed of subjects who are instructed not to exercise.
03

Check for Blocking

Yes, the study uses blocking. The blocking variable here is the age group, as the study ensures that the participants are stratified into age groups (18-30, 31-40, 41-55) before the random assignment.
04

Assess for Blinding

The study does not use blinding. Blinding occurs when participants or researchers do not know which group participants belong to, but here, participants are aware of whether or not they exercise.
05

Evaluate Causality and Generalization

Since this study is a randomized controlled trial, it can help establish causality between exercise and mental health outcomes. However, generalization might be limited if the initial population sample is not representative of the broader demographic.
06

Consider Reservations for Funding Decision

Reservations might include whether the study accounts for confounding variables such as dietary habits or stress levels, the duration of the study to observe potential changes, and the quality of the mental health exam utilized. Ensuring these factors are rigorously controlled or accounted for can influence the decision to fund the study.

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!

Key Concepts

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

Randomized Controlled Trial
In scientific research, a randomized controlled trial (RCT) is considered the gold standard for determining the efficacy of an intervention. An RCT primarily focuses on reducing bias by randomly assigning participants into either a treatment group or a control group. In the case of studying exercise effects on mental health, participants would be split into those who exercise and those who don鈥檛.
The beauty of randomization lies in achieving balance among groups. This reduces the potential influence of confounding variables that could skew results. It's crucial for the integrity of the study to ensure that every participant has an equal chance of being assigned to any group.
Conducting an RCT ensures a more definitive answer to whether exercise truly affects mental health in the way proposed by the hypothesis.
Stratified Sampling
Stratified sampling is a technique used to ensure that subgroups within a population are adequately represented in a study. It involves dividing the population into strata based on specific characteristics, such as age. For the exercise and mental health study, participants were divided into age groups (18-30, 31-40, and 41-55).
This approach enhances the accuracy of results by providing more representative samples of the population, especially when certain subgroups could behave differently. By ensuring proportional representation of various age groups, the resulting data is more reliably applicable to the overall population.
Stratified sampling can improve the power of a study by ensuring that all relevant subgroups are included, which is particularly important in a study examining varied effects of exercise on different age ranges.
Causality
Establishing causality refers to determining whether one variable directly affects another. In the context of this study, the goal is to see if regular exercise causes an improvement in mental health.
Randomized controlled trials inherently support causal claims due to their design. By controlling for external variables and using random assignment, researchers can better determine if observed changes are indeed due to the intervention (exercise, in this case).
However, it's essential to consider any lurking variables that could interfere, such as individual life stressors or different baseline mental health statuses, which might still impact the results even with the RCT design. Carefully accounting for these in the analysis strengthens the causal inference.
Blinding
Blinding is an essential aspect of experimental design intended to reduce bias. It involves keeping participants or even the researchers unaware of which individuals are in the treatment or control groups. Sadly, this study on exercise and mental health does not employ blinding, as participants are inherently aware of their exercise regimen.
Even though blinding might not be applicable here, researchers must take extra care to mitigate other potential biases. Awareness of group assignments could lead to placebo effects, where simply believing in an intervention leads to subjective improvements in outcomes.
Consideration of how to address knowledge of assignments鈥� effects in the analysis or through secondary measures can support the study's validity despite the absence of traditional blinding strategies.
Control Group
A control group is a fundamental component of experimental research used to establish a baseline for comparison. In the study regarding exercise and mental health, the control group includes those who do not participate in any exercise.
This group is crucial because it allows researchers to observe what happens when the variable of interest (exercise) is absent. This way, any changes in the treatment group鈥檚 mental health can be linked more confidently to the exercise intervention rather than external factors.
The careful selection and maintenance of a control group help ensure that the study's findings have a solid foundation, making it possible to compare outcomes accurately and apply those findings to broader contexts.

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

Identify the flaw in reasoning in the following scenarios. Explain what the individuals in the study should have done differently if they wanted to make such strong conclusions. (a) Students at an elementary school are given a questionnaire that they are required to return after their parents have completed it. One of the questions asked is, "Do you find that your work schedule makes it difficult for you to spend time with your kids after school?" Of the parents who replied, \(85 \%\) said "no". Based on these results, the school officials conclude that a great majority of the parents have no difficulty spending time with their kids after school. (b) A survey is conducted on a simple random sample of 1,000 women who recently gave birth, asking them about whether or not they smoked during pregnancy. A follow-up survey asking if the children have respiratory problems is conducted 3 years later, however, only 567 of these women are reached at the same address. The researcher reports that these 567 women are representative of all mothers. (c) A orthopedist administers a questionnaire to 30 of his patients who do not have any joint problems and finds that 20 of them regularly go running. He concludes that running decreases the risk of joint problems.

Office productivity is relatively low when the employees feel no stress about their work or job security. However, high levels of stress can also lead to reduced employee productivity. Sketch a plot to represent the relationship between stress and productivity.

Below are excerpts from two articles published in the NY Times: (a) An article called Risks: Smokers Found More Prone to Dementia states the following: \({ }^{57}\) "Researchers analyzed the data of 23,123 health plan members who participated in a voluntary exam and health behavior survey from 1978 to \(1985,\) when they were 50 to 60 years old. Twenty-three years later, about one-quarter of the group, or \(5,367,\) had dementia, including 1,136 with Alzheimers disease and 416 with vascular dementia. After adjusting for other factors, the researchers concluded that pack-a-day smokers were 37 percent more likely than nonsmokers to develop dementia, and the risks went up sharply with increased smoking; 44 percent for one to two packs a day; and twice the risk for more than two packs." Based on this study, can we conclude that smoking causes dementia later in life? Explain your reasoning. (b) Another article called The School Bully Is Sleepy states the following: 5 "The University of Michigan study, collected survey data from parents on each child's sleep habits and asked both parents and teachers to assess behavioral concerns. About a third of the students studied were identified by parents or teachers as having problems with disruptive behavior or bullying. The researchers found that children who had behavioral issues and those who were identified as bullies were twice as likely to have shown symptoms of sleep disorders." A friend of yours who read the article says, "The study shows that sleep disorders lead to bullying in school children." Is this statement justified? If not, how best can you describe the conclusion that can be drawn from this study?

Identify which value represents the sample mean and which value represents the claimed population mean. (a) A recent article in a college newspaper stated that college students get an average of \(5.5 \mathrm{hrs}\) of sleep each night. A student who was skeptical about this value decided to conduct a survey by randomly sampling 25 students. On average, the sampled students slept 6.25 hours per night. (b) American households spent an average of about $$\$ 52$$ in 2007 on Halloween merchandise such as costumes, decorations and candy. To see if this number had changed, researchers conducted a new survey in 2008 before industry numbers were reported. The survey included 1,500 households and found that average Halloween spending was $$\$ 58$$ per household. (c) The average GPA of students in 2001 at a private university was 3.37 . A survey on a sample of 203 students from this university yielded an average GPA of 3.59 in Spring semester of 2012 .

A large college class has 160 students. All 160 students attend the lectures together, but the students are divided into 4 groups, each of 40 students, for lab sections administered by different teaching assistants. The professor wants to conduct a survey about how satisfied the students are with the course, and he believes that the lab section a student is in might affect the student's overall satisfaction with the course. (a) What type of study is this? (b) Suggest a sampling strategy for carrying out this study.
See all solutions

Recommended explanations on Math Textbooks

Probability and Statistics

Read Explanation

Calculus

Read Explanation

Pure Maths

Read Explanation

Applied Mathematics

Read Explanation

Statistics

Read Explanation

Decision Maths

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.