Mathematical Statistics with Applications
7th Edition
ISBN: 9780495110811
Author: Dennis Wackerly, William Mendenhall, Richard L. Scheaffer
Publisher: Cengage Learning
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Chapter 14.5, Problem 23E
The χ2 test used in Exercise 14.22 is equivalent to the two-tailed Z test of Section 10.3, provided α is the same for the two tests. Show algebraically that the χ2 test statistic X2 is the square of the test statistic Z for the equivalent test.
14.22 A study to determine the effectiveness of a drug (serum) for the treatment of arthritis resulted in the comparison of two groups each consisting of 200 arthritic patients. One group was inoculated with the serum whereas the other received a placebo (an inoculation that appears to contain serum but actually is not active). After a period of time, each person in the study was asked whether his or her arthritic condition had improved. The results in the accompanying table were observed. Do these data present sufficient evidence to indicate that the proportions of arthritic individuals who said their condition had improved differed depending on whether they received the serum?
- a Test by using the X2 statistic. Use α = .05.
- b Test by using the Z test of Section 10.3 and α = .05. Compare your result with that in part (a).
- c Give bounds for the attained significance level associated with the test in part (a).
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Example 4 (Part 2) We can use Statkey to take 50 different random samples of size 20 each, find the mean of
each sample, and compute a confidence interval for each one. The graph of the sampling distribution of the means
is on the left below, and that of the 50 confidence intervals is on the right.
1. What does each dot on the left hand dotplot represent?
StatKey Sampling Distribution for a Mean
Percent with Internet Access (Countries) ▾
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20
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Sampling Dotplot of Mean
Left Tail Two-Tail Right Tail
60
50
40
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30
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10
samples = 50
mean = 41.626
std. error = 5.089
:
.:
:
::
0
25
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55
60
41.626
Data Plots
Confidence Intervals
95%->
Confidence Intervals
Coverage
48/50 = 96%
20
40
60
80
2. Circle the confidence intervals that failed to capture the true mean.
3. Circle the sample means that produced those…
Example 4 (Part 1) One of the datasets in the Lock book
contains information about 215 countries of the world. One
of the variables is the percentage of people in the country
who have access to the internet. We have data for 203 of
those countries. The plot on the right shows a dotplot of
the data.
1. What are the cases?
Population
n = 203, mean = 43.024
median = 43.5, stdev = 29.259
20
2. What does each dot on the dotplot represent?
15
10
5
20
40
43.024
60
80
3. What type of data is do we collect from the cases, quantitative or categorical?
Let x be a random variable that represents the percentage of successful free throws a professional basketball player makes in a season. Let y be a random variable that represents the percentage of successful field goals a professional basketball player makes in a season. A random sample of n =6 professional basketball players gave the following information.
x
63
79
70
80
84
87
y
46
49
45
55
57
58
Find Se. Round your answer to three decimal places.
Chapter 14 Solutions
Mathematical Statistics with Applications
Ch. 14.3 - Historically, the proportions of all Caucasians in...Ch. 14.3 - Prob. 2ECh. 14.3 - Prob. 3ECh. 14.3 - Prob. 4ECh. 14.3 - Prob. 5ECh. 14.3 - Prob. 6ECh. 14.3 - Prob. 7ECh. 14.3 - Prob. 8ECh. 14.3 - Prob. 9ECh. 14.3 - Prob. 10E
Ch. 14.3 - The data in the following table are the frequency...Ch. 14.4 - On the 40th anniversary of President John F....Ch. 14.4 - A study was conducted by Joseph Jacobson and Diane...Ch. 14.4 - Suppose that the entries in a contingency table...Ch. 14.4 - A survey to explore the relationship between...Ch. 14.4 - Prob. 17ECh. 14.4 - Prob. 18ECh. 14.4 - The results of a study suggest that the initial...Ch. 14.4 - Refer to Exercise 14.10. Test the hypothesis, at...Ch. 14.4 - An interesting and practical use of the 2 test...Ch. 14.5 - A study to determine the effectiveness of a drug...Ch. 14.5 - The 2 test used in Exercise 14.22 is equivalent to...Ch. 14.5 - How do Americans in the sandwich generation...Ch. 14.5 - Does education really make a difference in how...Ch. 14.5 - A manufacturer of buttons wished to determine...Ch. 14.5 - Traditionally, U.S. labor unions have been content...Ch. 14.5 - Prob. 29ECh. 14.5 - Refer to Exercise 14.29. Estimate the difference...Ch. 14.5 - A survey was conducted to investigate interest of...Ch. 14 - Prob. 32SECh. 14 - A survey was conducted to determine student,...Ch. 14 - How would you rate yourself as a driver? According...Ch. 14 - Prob. 35SECh. 14 - Knee injuries are a major problem for athletes in...Ch. 14 - It is often not clear whether all properties of a...Ch. 14 - Prob. 39SECh. 14 - Prob. 40SECh. 14 - Prob. 41SECh. 14 - Prob. 42SECh. 14 - Prob. 43SE
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