Intro Stats
4th Edition
ISBN: 9780321825278
Author: Richard D. De Veaux, Paul F. Velleman, David E. Bock
Publisher: PEARSON
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Textbook Question
Chapter 11, Problem 50E
Swimming Recently, a group of adults who swim regularly for exercise were evaluated for depression. It turned out that these swimmers were less likely to be depressed than the general population. The researchers said the difference was statistically significant.
- a) What does “statistically significant” mean in this context?
- b) Is this an experiment or an observational study? Explain.
- c) News reports claimed this study proved that swimming can prevent depression. Explain why this conclusion is not justified by the study. Include an example of a possible lurking variable.
- d) But perhaps it is true. We wonder if exercise can ward off depression, and whether anaerobic exercise (like weight training) is as effective as aerobic exercise (like swimming). We find 120 volunteers not currently engaged in a regular program of exercise. Design an appropriate experiment.
Expert Solution & Answer
Learn your wayIncludes step-by-step video
schedule19:13
Students have asked these similar questions
(a) Test the hypothesis.
Consider the hypothesis test Ho
=
:
against H₁o < 02. Suppose that the sample sizes aren₁ =
7 and n₂
= 13 and that
$²
= 22.4 and $22
= 28.2. Use α = 0.05.
Ho
is not
✓ rejected.
9-9
IV
(b) Find a 95% confidence interval on of 102. Round your answer to two decimal places (e.g. 98.76).
Let us suppose we have some article reported on a study of potential sources of injury to equine veterinarians conducted at a
university veterinary hospital. Forces on the hand were measured for several common activities that veterinarians engage in when
examining or treating horses. We will consider the forces on the hands for two tasks, lifting and using ultrasound. Assume that both
sample sizes are 6, the sample mean force for lifting was 6.2 pounds with standard deviation 1.5 pounds, and the sample mean force
for using ultrasound was 6.4 pounds with standard deviation 0.3 pounds. Assume that the standard deviations are known.
Suppose that you wanted to detect a true difference in mean force of 0.25 pounds on the hands for these two activities. Under the null
hypothesis, 40 = 0. What level of type II error would you recommend here?
Round your answer to four decimal places (e.g. 98.7654). Use a
= 0.05.
β
= i
What sample size would be required?
Assume the sample sizes are to be equal.…
=
Consider the hypothesis test Ho: μ₁ = μ₂ against H₁ μ₁ μ2. Suppose that sample sizes are n₁ =
15 and n₂ =
15, that x1 = 4.7
and X2 = 7.8 and that s² = 4 and s² = 6.26. Assume that o and that the data are drawn from normal distributions. Use
απ 0.05.
(a) Test the hypothesis and find the P-value.
(b) What is the power of the test in part (a) for a true difference in means of 3?
(c) Assuming equal sample sizes, what sample size should be used to obtain ẞ = 0.05 if the true difference in means is - 2? Assume
that α = 0.05.
(a) The null hypothesis is
98.7654).
rejected. The P-value is 0.0008
(b) The power is 0.94
. Round your answer to four decimal places (e.g.
Round your answer to two decimal places (e.g. 98.76).
(c) n₁ = n2 =
1
. Round your answer to the nearest integer.
Chapter 11 Solutions
Intro Stats
Ch. 11.3 - At one time, a method called gastric freezing was...Ch. 11.4 - Recall the experiment about gastric freezing, an...Ch. 11 - Steroids The 1990s and early 2000s could be...Ch. 11 - Prob. 2ECh. 11 - Prob. 3ECh. 11 - Tomatoes You want to compare the tastiness and...Ch. 11 - Tips II For the experiment described in Exercise...Ch. 11 - Prob. 6ECh. 11 - Prob. 7ECh. 11 - Prob. 8E
Ch. 11 - Prob. 9ECh. 11 - Prob. 10ECh. 11 - Block that tip The driver of Exercise 3 wants to...Ch. 11 - Blocking tomatoes To obtain enough plants for the...Ch. 11 - Prob. 13ECh. 11 - Prob. 14ECh. 11 - Standardized test scores For his statistics class...Ch. 11 - Heart attacks and height Researchers who examined...Ch. 11 - Prob. 17ECh. 11 - Prob. 18ECh. 11 - Menopause Researchers studied the herb black...Ch. 11 - Honesty Coffee stations in offices often just ask...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - 2134. Whats the design? Read each brief report of...Ch. 11 - Omega-3 Exercise 21 describes an experiment that...Ch. 11 - Insomnia Exercise 24 describes an experiment...Ch. 11 - Omega-3, revisited Exercises 21 and 35 describe an...Ch. 11 - Insomnia, again Exercises 24 and 36 describe an...Ch. 11 - Omega-3, finis Exercises 21, 35, and 37 describe...Ch. 11 - Insomnia, at last Exercises 24, 36, and 38...Ch. 11 - Injuries Exercise 33 describes an experiment that...Ch. 11 - Tomatoes II Describe a strategy to randomly split...Ch. 11 - Shoes A running-shoe manufacturer wants to test...Ch. 11 - Swimsuits A swimsuit manufacturer wants to test...Ch. 11 - Hamstrings Exercise 33 discussed an experiment to...Ch. 11 - Diet and blood pressure An experiment showed that...Ch. 11 - Mozart Will listening to a Mozart piano sonata...Ch. 11 - Contrast baths Contrast bath treatments use the...Ch. 11 - Prob. 49ECh. 11 - Swimming Recently, a group of adults who swim...Ch. 11 - Dowsing Before drilling for water, many rural...Ch. 11 - Healing A medical researcher suspects that giving...Ch. 11 - Reading Some schools teach reading using phonics...Ch. 11 - Gas mileage Do cars get better gas mileage with...Ch. 11 - Weekend deaths A study published in the New...Ch. 11 - Shingles A research doctor has discovered a new...Ch. 11 - Beetles Hoping to learn how to control crop damage...Ch. 11 - SAT prep Can special study courses actually help...Ch. 11 - Safety switch An industrial machine requires an...Ch. 11 - Washing clothes A consumer group wants to test the...Ch. 11 - Skydiving, anyone? A humor piece published in the...
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