Statistics, Books a la Carte Edition Plus MyLab Statistics with Pearson eText -- Access Card Package (4th Edition)
4th Edition
ISBN: 9780134435855
Author: Alan Agresti, Christine A. Franklin, Bernhard Klingenberg
Publisher: PEARSON
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Textbook Question
Chapter 9.2, Problem 22PB
Garlic to repel ticks A study (J. Amer. Med. Assoc., vol. 284, p. 831, 2000) considered whether daily consumption of 1200 mg of garlic could reduce tick bites. The study used a crossover design with a sample of Swedish military conscripts, half of whom used placebo first and garlic second and half the reverse. The authors did not present the data, but the effect they described is consistent with garlic being more effective with 37 subjects and placebo being more effective with 29 subjects. Does this suggest a real difference between garlic and placebo, or are the results consistent with random variation? Answer by:
- a. Identifying the relevant variable and parameter. (Hint: The variable is categorical with two categories. The parameter is a population proportion for one of the categories.)
- b. Stating hypotheses for a large-sample two-sided test and checking that
sample size guidelines are satisfied for that test. - c. Finding the test statistic value.
- d. Finding and interpreting a P-value and stating the conclusion in context.
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- A study (J. Amer. Med. Assoc., vol. 284, p. 831, 2000) considered whether daily consumption of 1200 mg of garlic could reduce tick bites. The study used a crossover design with a sample of Swedish military conscripts, half of whom used placebo first and garlic second and half the reverse. The authors did not present the data, but the effect they described is consistent with garlic being more effective with 37 subjects and placebo being more effective with 29 subjects. Does this suggest a real difference between garlic and placebo, or are the results consistent with random variation?
Calcium and Blood Pressure Does increasing the amount of calcium in our diet reduce blood
pressure? Examination of a large sample of people revealed a relationship between calcium intake
and blood pressure. Such observational studies do not establish causation. Researchers therefore
designed a randomized comparative experiment.
The subjects were 21 healthy men who volunteered to take part in the experiment. They were
randomly assigned to two groups: 10 of the men received a calcium supplement for 12 weeks,
while the control group of 11 men received a placebo pill that looked identical. The experiment
was double-blind. The response variable is the decrease in systolic (top number) blood pressure
for a subject after 12 weeks, in millimeters of mercury. An increase appears as a negative number.
Do the data provide convincing evidence that a calcium supplement reduces blood pressure more
than a placebo, on average, for subjects like the ones in this study?
Group 1 (calcium)
Group (placebo)…
One study of cell phones and the risk of brain cancer looked at a group of 469 people who have brain cancer. The investigators then asked about the use of cell phones. Result: “Our data suggest that the use of hand- held cellular phones is not associated with risk of brain cancer.
B . Based on this study, can you determine that cellular use does not CAUSE brain cancer? Why or why not?
Chapter 9 Solutions
Statistics, Books a la Carte Edition Plus MyLab Statistics with Pearson eText -- Access Card Package (4th Edition)
Ch. 9.1 - H0 or Ha? For parts a and b, is the statement a...Ch. 9.1 - H0 or Ha? For each of the following, is the...Ch. 9.1 - Burden of proof For a new pesticide, should the...Ch. 9.1 - Financial aid The average financial aid package...Ch. 9.1 - Low-carbohydrate diet A study plans to have a...Ch. 9.1 - Prob. 6PBCh. 9.1 - Proper hypotheses? Explain what is wrong with each...Ch. 9.1 - Prob. 8PBCh. 9.1 - P-value Indicate whether each of the following...Ch. 9.2 - Psychic A person who claims to be psychic says he...
Ch. 9.2 - Prob. 11PBCh. 9.2 - Get P-value from z For a test of H0: p = 0.50, the...Ch. 9.2 - Get more P-values from z Refer to the previous...Ch. 9.2 - Find test statistic and P-value For a test of H0:...Ch. 9.2 - Dogs and cancer A recent study4 considered whether...Ch. 9.2 - Religion important in your life? Americans ages 18...Ch. 9.2 - Prob. 17PBCh. 9.2 - Prob. 18PBCh. 9.2 - Testing a headache remedy Studies that compare...Ch. 9.2 - Gender bias in selecting managers For a large...Ch. 9.2 - Gender discrimination Refer to the 95% confidence...Ch. 9.2 - Garlic to repel ticks A study (J. Amer. Med....Ch. 9.2 - Exit-poll predictions According to an exit poll of...Ch. 9.2 - Which cola? The 49 students in a class at the...Ch. 9.2 - How to sell a burger A fast-food chain wants to...Ch. 9.2 - A binomial headache A null hypothesis states that...Ch. 9.2 - P-value for small samples Example 4, on whether...Ch. 9.3 - Which t has P-value = 0.05? A t test for a mean...Ch. 9.3 - Practice mechanics of a t test A study has a...Ch. 9.3 - Prob. 30PBCh. 9.3 - Low carbohydrate diet In a recent study,8 272...Ch. 9.3 - Prob. 32PBCh. 9.3 - Facebook friends Many students brag that they have...Ch. 9.3 - Lake pollution An industrial plant claims to...Ch. 9.3 - Weight change for controls A disadvantage of the...Ch. 9.3 - Crossover study A crossover study of 13 children...Ch. 9.3 - Too little or too much wine? Wine-pouring vending...Ch. 9.3 - Prob. 38PBCh. 9.3 - Assumptions important? Refer to the previous...Ch. 9.3 - Anorexia in teenage girls Example 8 described a...Ch. 9.3 - Sensitivity study Ideally, results of a...Ch. 9.3 - Prob. 42PBCh. 9.4 - Dr. Dog In the experiment in Example 4, we got a...Ch. 9.4 - Error probability A significance test about a...Ch. 9.4 - Fracking errors Example 6, in testing H0: p = 0.5...Ch. 9.4 - Prob. 46PBCh. 9.4 - Anorexia decision Refer to the previous exercise....Ch. 9.4 - Prob. 48PBCh. 9.4 - Errors in medicine Consider the test of H0: The...Ch. 9.4 - Prob. 50PBCh. 9.4 - Detecting prostate cancer Refer to the previous...Ch. 9.4 - Prob. 52PBCh. 9.5 - Misleading summaries? Two researchers conduct...Ch. 9.5 - Practical significance A study considers whether...Ch. 9.5 - Prob. 55PBCh. 9.5 - Fishing for significance A marketing study...Ch. 9.5 - Prob. 57PBCh. 9.5 - Prob. 58PBCh. 9.5 - Interpret medical research studies a. An...Ch. 9.6 - Find P(Type II error) A study is designed to test...Ch. 9.6 - Gender bias in selecting managers Exercise 9.20...Ch. 9.6 - Prob. 62PBCh. 9.6 - P(Type II error) large when p close to H0 For...Ch. 9.6 - Prob. 64PBCh. 9.6 - Power for infertility trial Consider Example 13...Ch. 9.6 - Exploring Type II errors Refer to the web app from...Ch. 9 - H0 or Ha? For each of the following hypotheses,...Ch. 9 - Write H0 and Ha For each of the following...Ch. 9 - Prob. 69CPCh. 9 - Free-throw accuracy Consider all cases in which a...Ch. 9 - Brown or Whitman? Californias governor election in...Ch. 9 - Prob. 72CPCh. 9 - Prob. 73CPCh. 9 - Prob. 74CPCh. 9 - Prob. 75CPCh. 9 - Start a hockey team A fraternity at a university...Ch. 9 - Prob. 77CPCh. 9 - Prob. 78CPCh. 9 - Prob. 79CPCh. 9 - Prob. 80CPCh. 9 - Prob. 81CPCh. 9 - Two ideal children? Is the ideal number of...Ch. 9 - Prob. 83CPCh. 9 - Prob. 84CPCh. 9 - Blood pressure When Vincenzo Baranellos blood...Ch. 9 - Increasing blood pressure In the previous...Ch. 9 - Tennis balls in control? When it is operating...Ch. 9 - Prob. 88CPCh. 9 - Prob. 89CPCh. 9 - CI and test Refer to the previous exercise. a. For...Ch. 9 - Prob. 91CPCh. 9 - Religious beliefs statistically significant? A...Ch. 9 - Prob. 93CPCh. 9 - Prob. 94CPCh. 9 - Prob. 95CPCh. 9 - Prob. 96CPCh. 9 - Prob. 98CPCh. 9 - Baseball home team advantage In Major League...Ch. 9 - Prob. 100CPCh. 9 - Prob. 101CPCh. 9 - Prob. 102CPCh. 9 - Prob. 103CPCh. 9 - Prob. 104CPCh. 9 - Prob. 105CPCh. 9 - Prob. 106CPCh. 9 - Prob. 107CPCh. 9 - Prob. 108CPCh. 9 - Significance Explain the difference between...Ch. 9 - More doctors recommend An advertisement by Company...Ch. 9 - Prob. 111CPCh. 9 - Bad P-value interpretations A random sample of...Ch. 9 - Prob. 113CPCh. 9 - Prob. 114CPCh. 9 - Prob. 115CPCh. 9 - Prob. 116CPCh. 9 - Prob. 117CPCh. 9 - Prob. 118CPCh. 9 - Prob. 119CPCh. 9 - Prob. 120CPCh. 9 - Prob. 121CPCh. 9 - True or false A 95% confidence interval for =...Ch. 9 - Prob. 123CPCh. 9 - Prob. 124CPCh. 9 - Prob. 125CPCh. 9 - Prob. 126CPCh. 9 - Prob. 127CPCh. 9 - Prob. 128CP
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