In the United States, approximately 450,000 vasectomies are performed each year. In this surgical procedure for contraception, the tube carrying sperm from the testicles is cut and tied. Several studies have been conducted to analyze the relationship between vasectomies and prostate cancer. The results of one such study by E. Giovannucci et al. appeared in the paper “A Retrospective Cohort Study of Vasectomy and Prostate Cancer in U.S. Men” (Journal of the American Medical Association, Vol. 269(7), pp. 878–882). Of 21,300 men who had not had a vasectomy, 69 were found to have prostate cancer; of 22,000 men who had had a vasectomy, 113 were found to have prostate cancer. a. At the 1% significance level, do the data provide sufficient evidence to conclude that men who have had a vasectomy are at greater risk of having prostate cancer? Consider men who had had a vasectomy Population 2. b. Is this study a designed experiment or an observational study? Explain your answer. c. In view of your answers to parts (a) and (b), could you reasonably conclude that having a vasectomy causes an increased risk of prostate cancer? Explain your answer.
> We have given a likely range for the observed value of a sample proportion p^. a. Based on the given range, identify the educated guess that should be used for the observed value of p to calculate the required sample size for a prescribed confidence leve
> We have given a likely range for the observed value of a sample proportion p^. a. Based on the given range, identify the educated guess that should be used for the observed value of p to calculate the required sample size for a prescribed confidence leve
> We have given a likely range for the observed value of a sample proportion p^. a. Based on the given range, identify the educated guess that should be used for the observed value of p to calculate the required sample size for a prescribed confidence leve
> We have given a likely range for the observed value of a sample proportion p^. a. Based on the given range, identify the educated guess that should be used for the observed value of p to calculate the required sample size for a prescribed confidence leve
> Why is statistical inference generally used to obtain information about a population proportion?
> We have given a likely range for the observed value of a sample proportion p^. a. Based on the given range, identify the educated guess that should be used for the observed value of p to calculate the required sample size for a prescribed confidence leve
> A study by researchers at the University of Maryland addressed the question of whether the mean body temperature of humans is 98.6◦F. The results of the study by P. Mackowiak et al. appeared in the article “A Critical Appraisal of 98.6◦F, the Upper Limit
> According to an article in Science News, binge eating has been associated with a mutation of the gene for a brain protein called melanocortin 4 receptor (MC4R). In one study, F. Horber of the Hirslanden Clinic in Zurich and his colleagues genetically ana
> A Harris Poll asked Americans whether states should be allowed to conduct random drug tests on elected officials. Of 21,355 respondents, 79% said “yes.” a. Determine the margin of error for a 99% confidence interval. b. Without doing any calculations, in
> From the U.S. Census Bureau document America’s Families and Living Arrangements and an article in Time magazine, we found that, in 1963, 83.0% of American women between the ages of 25 and 54 were married, compared to 64.6% in 2010. a. For 2010, identify
> From Wikipedia’s on-line document “List of First Overall NBA Draft Picks,” we found that, since 1947, 10.4% of the number-one draft picks in the National Basketball Association have been other than U.S. nationals. a. Identify the population. b. Identify
> Prerequisite to this exercise are Exercises 11.9–11.13. What do your graphs in parts (c) of those exercises illustrate about the impact of increasing sample size on sampling error? Explain your answer. Data from Exercise 11.13: This exercise involves th
> Repeat Exercise 11.136 by applying the formula in Exercise 11.134(a) if you can reasonably presume that at most 41% of the men sampled and at most 49% of the women sampled will be people who sometimes order veg. Compare the results obtained in Exercise 1
> Refer to the study on ordering vegetarian. a. Without making a guess for the observed values of the sample proportions, find the common sample size that will ensure a margin of error of at most 0.01 for a 90% confidence interval. b. Find a 90% confidence
> Refer to the study on ordering vegetarian. a. Obtain the margin of error for the estimate of the difference between the proportions of men and women who sometimes order veg by taking half the length of the confidence interval found. Interpret your answer
> Suppose that you can make reasonably good educated guesses, pˆ1g and pˆ2g, for the observed values of pˆ1 and pˆ2. a. Use your result from Exercise 11.132 to show that a (1 − α)-level confidence interval for the difference between two population proporti
> Use your result from Exercise 11.132 to show that a (1 − α) level confidence interval for the difference between two population proportions that has a margin of error of at most E can be obtained by choosing rounded up to the nearest whole number.
> As reported by the U.S. Census Bureau in the document Educational Attainment in the United States, the percentage of adults in each state and the District of Columbia who have completed a bachelor’s degree is provided on the WeissStats site. a. use the t
> Obtain a formula for the margin of error, E, in estimating the difference between two population proportions by referring to Step 2 of Procedure.
> A Wall Street Journal article, titled “Hypertension Drug Linked to Cancer,” reported on a study of several types of high-blood-pressure drugs and links to cancer. For one type, called calcium channel blockers, 27 of 202 elderly patients taking the drug d
> The Quinnipiac University Poll conducts nationwide surveys as a public service and for research. In one poll, participants were asked whether they thought eliminating the federal gas tax for the summer months is a good idea. The following problems are ba
> Repeat parts (b)–(e) of Exercise 11.9 for samples of size 5. Data from Exercise 11.9: This exercise involves the use of an unrealistically small population to provide a concrete illustration for the exact distribution of a sample proportion. A populatio
> Use the two-proportions plus four z-interval procedure to find the required confidence interval. Interpret your results. The Organization for Economic Cooperation and Development (OECD) conducts studies on unemployment rates by country and publishes its
> Use the two-proportions plus four z-interval procedure to find the required confidence interval. Interpret your results. Since 1973, Gallup has asked Americans how much confidence they have in a variety of U.S. institutions. One question asked of those p
> x1 = 30, n1 = 80, x2 = 15, n2 = 20; 95% confidence interval a. use the two-proportions plus-four z-interval procedure to find the required confidence interval for the difference between the two population proportions. b. compare your result with the corr
> x1 = 18, n1 = 30, x2 = 10, n2 = 20; 95% confidence interval a. use the two-proportions plus-four z-interval procedure to find the required confidence interval for the difference between the two population proportions. b. compare your result with the corr
> x1 = 15, n1 = 20, x2 = 18, n2 = 30; 90% confidence interval a. use the two-proportions plus-four z-interval procedure to find the required confidence interval for the difference between the two population proportions. b. compare your result with the corr
> x1 = 14, n1 = 20, x2 = 8, n2 = 20; 90% confidence interval a. use the two-proportions plus-four z-interval procedure to find the required confidence interval for the difference between the two population proportions. b. compare your result with the corre
> As reported by the U.S. Census Bureau in Educational Attainment in the United States, the percentage of adults in each state and the District of Columbia who have completed high school is provided on the WeissStats site. a. use the technology of your cho
> x1 = 18, n1 = 40, x2 = 30, n2 = 40; 80% confidence interval a. use the two-proportions plus-four z-interval procedure to find the required confidence interval for the difference between the two population proportions. b. compare your result with the corr
> x1 = 10, n1 = 20, x2 = 18, n2 = 30; 80% confidence interval a. use the two-proportions plus-four z-interval procedure to find the required confidence interval for the difference between the two population proportions. b. compare your result with the corr
> In the New York Times article “College Graduates Fare Well in Jobs Market, Even through Recession,” C. Rampell noted that college graduates have suffered through the recession and lackluster recovery with remarkable resilience. Of a random sample of 1020
> Neutropenia is an abnormally low number of neutrophils (a type of white blood cell) in the blood. Chemotherapy often reduces the number of neutrophils to a level that makes patients susceptible to fever and infections. G. Bucaneve et al. published a stud
> Repeat parts (b)–(e) of Exercise 11.9 for samples of size 4. Data from Exercise 11.9: This exercise involves the use of an unrealistically small population to provide a concrete illustration for the exact distribution of a sample proportion. A populatio
> The Organization for Economic Cooperation and Development (OECD) summarizes data on labor-force participation rates in OECD in Figures. Independent simple random samples were taken of 300 U.S. women and 250 Canadian women. Of the U.S. women, 215 were fou
> An issue of Science News (Vol. 163, No. 22, pp. 341–342) reported that the Women’s Health Initiative cast doubts on the benefit of hormone-replacement therapy. Researchers randomly divided 4532 healthy women over the age of 65 years into two groups. One
> Apply Procedure to find the required confidence interval. Refer to Exercise 11.111 and find and interpret a 90% confidence interval for the difference between the percentages of adults in the two degree categories who have an above healthy weight. Data
> Apply Procedure to find the required confidence interval. Refer to Exercise 11.110 and find and interpret a 98% confidence interval for the difference between the percentages of women and men who favor ballistic fingerprinting. Data from Exercise 11.110
> Apply Procedure to find the required confidence interval. Refer to Exercise 11.109 and find and interpret a 99% confidence interval for the difference between the proportions of seat-belt users for drivers in the age groups 16–24 years and 25–69 years.
> In the article, “Length of The Beatles’ Songs” (Chance, Vol. 25, No. 1, pp. 30–33), T. Koyama discusses aspects and interpretations of the lengths of songs by The Beatles. Data on the length, in seconds, of 229 Beatles’ songs are presented on the WeissSt
> Apply Procedure to find the required confidence interval. Refer to Exercise 11.108 and find and interpret a 95% confidence interval for the difference between the stroke incidences of white and African-American elderly. Data from Exercise 11.108: In the
> Apply Procedure to find the required confidence interval. Refer to Exercise 11.107 and determine and interpret a 98% confidence interval for the difference between the rates of major birth defects for babies born to women who have taken folic acid and th
> Apply Procedure to find the required confidence interval. Refer to Exercise 11.106 and determine and interpret a 98% confidence interval for the difference between the prostate cancer rates of men who have had a vasectomy and those who have not. Data fr
> Body mass index (BMI) is a measure of body fat based on height and weight. According to the document Dietary Guidelines for Americans, published by the U.S. Department of Agriculture and the U.S. Department of Health and Human Services, for adults, a BMI
> Guns make unique markings on bullets they fire and their shell casings. These markings are called ballistic fingerprints. An ABCNEWS Poll examined the opinions of Americans on the enactment of a law “. . .that would require every gun sold in the United S
> Repeat parts (b)–(e) of Exercise 11.9 for samples of size 3. Data from Exercise 11.9: This exercise involves the use of an unrealistically small population to provide a concrete illustration for the exact distribution of a sample proportion. A populatio
> The National Highway Traffic Safety Administration collects data on seat-belt use and publishes results in the document Occupant Restraint Use. Of 1000 drivers 16–24 years old, 79% said that they buckle up, whereas 924 of 1100 drivers 25–69 years old sai
> In the paper “The Racial Crossover in Comorbidity, Disability, and Mortality” (Demography, Vol. 37(3), pp. 267–283), N. Johnson investigated the health of independent random samples of white and African-American elderly (aged 70 years or older). Of the 4
> For several years, evidence had been mounting that folic acid reduces major birth defects. A. Czeizel and I. Dudas of the National Institute of Hygiene in Budapest directed a study that provided the strongest evidence to date. Their results were publishe
> In an article titled “Great White, Deep Trouble” (National Geographic, Vol. 197(4), pp. 2–29), Peter Benchley—the author of JAWS—discussed various aspects of the Great White Shark (Carcharodon carcharias). Data on the number of pups borne in a lifetime b
> In the 1940s and early 1950s, the public was greatly concerned about polio. In an attempt to prevent this disease, Jonas Salk of the University of Pittsburgh developed a polio vaccine. In a test of the vaccine’s efficacy, involving nearly 2 million grade
> x1 = 30, n1 = 80, x2 = 15, n2 = 20; two-tailed test, α = 0.05; 95% confidence interval We have provided the numbers of successes and the sample sizes for independent simple random samples from two populations. a. Determine the sample proportions. b. Deci
> x1 = 18, n1 = 30, x2 = 10, n2 = 20; two-tailed test, α = 0.05; 95% confidence interval We have provided the numbers of successes and the sample sizes for independent simple random samples from two populations. a. Determine the sample proportions. b. Deci
> x1 = 15, n1 = 20, x2 = 18, n2 = 30; right-tailed test, α = 0.05; 90% confidence interval We have provided the numbers of successes and the sample sizes for independent simple random samples from two populations. a. Determine the sample proportions. b. De
> x1 = 14, n1 = 20, x2 = 8, n2 = 20; right-tailed test, α = 0.05; 90% confidence interval We have provided the numbers of successes and the sample sizes for independent simple random samples from two populations. a. Determine the sample proportions. b. Dec
> x1 = 18, n1 = 40, x2 = 30, n2 = 40; left-tailed test, α = 0.10; 80% confidence interval We have provided the numbers of successes and the sample sizes for independent simple random samples from two populations. a. Determine the sample proportions. b. Dec
> x1 = 10, n1 = 20, x2 = 18, n2 = 30; left-tailed test, α = 0.10; 80% confidence interval We have provided the numbers of successes and the sample sizes for independent simple random samples from two populations. a. Determine the sample proportions. b. Dec
> Repeat parts (b)–(e) of Exercise 11.9 for samples of size 1. Data from Exercise 11.9: This exercise involves the use of an unrealistically small population to provide a concrete illustration for the exact distribution of a sample proportion. A populatio
> An independent golf equipment testing facility compared the difference in the performance of golf balls hit off a regular 2-3/4’’ wooden tee to those hit off a 3’’ Stinger Competition golf tee. A Callaway Great Big Bertha driver with 10 degrees of loft w
> L. Petersen et al. evaluated the effects of integrated treatment for patients with a first episode of psychotic illness in the paper “A Randomised Multicentre Trial of Integrated Versus Standard Treatment for Patients with a First Episode of Psychotic Il
> We conducted a non-pooled t-test, at the 5% significance level, to decide whether the mean operative time is less with the dynamic system than with the static system. Use the technology of your choice to perform the following tasks. a. Using a pooled t-t
> In the article “Trophic Interaction Cycles in Tundra Ecosystems and the Impact of Climate Change”, R. Ims and E. Fuglei provided an overview of animal species in the northern tundra. One threat to the snow goose in arctic Canada is the lemming. Snowy owl
> You conducted a non-pooled t-test to decide whether the mean number of acute postoperative days spent in the hospital is smaller with the dynamic system than with the static system. Use the technology of your choice to perform the following tasks. a. Usi
> A mutual fund is a professionally managed investment that can be sold to the general public. Mutual funds can be specialized into different categories such as healthcare-related or technology-related mutual funds. The following table lists the 3-month ra
> L. Grossback et al. examined mandate perceptions and their causes in the paper “Comparing Competing Theories on the Causes of Mandate Perceptions” (American Journal of Political Science, Vol. 49, Issue 2, pp. 406–419). The following are data on the perce
> In the article “Sleep Apnea in Adults With Traumatic Brain Injury: A Preliminary Investigation” (Archives of Physical Medicine and Rehabilitation, Vol. 82, Issue 3, pp. 316– 321), J. Webster et al. investigated sleep-related breathing disorders in adults
> Refer to Exercise 10.86 and find a 99% confidence interval for the difference between the mean wing lengths of the two subspecies. Data from Exercise 10.86: D. Cristol et al. published results of their studies of two subspecies of dark-eyed juncos in th
> Refer to Exercise 10.85 and determine a 98% confidence interval for the difference between the mean dopamine activities of psychotic and nonpsychotic patients. Data from Exercise 10.85: Previous research has suggested that changes in the activity of dop
> Refer to Exercise 10.84 and find a 90% confidence interval for the difference between the mean heart rates of urban bus drivers in Stockholm in the two environments. Data from Exercise 10.84: An intervention program designed by the Stockholm Transit Dis
> The primary concern is deciding whether the mean of Population 1 is less than the mean of Population 2. a. Determine the null and alternative hypotheses. b. Classify the hypothesis test as two tailed, left tailed, or right tailed.
> Refer to Exercise 10.83 and find a 90% confidence interval for the difference between the mean numbers of acute postoperative days in the hospital with the dynamic and static systems. Data from Exercise 10.83: The researchers also obtained the following
> Determine a 98% confidence interval for the difference, μ1 − μ2, between the mean sizes of malignant and benign phyllodes tumors.
> Old Faithful is a geyser in Yellowstone National Park that erupts at relatively predictable intervals. Since 2000, the eruptions of Old Faithfull occur on average every 90 minutes. Information on the daily eruptions of Old Faithful can be found on the we
> Obtain a 90% confidence interval for the difference, μ1 − μ2, between the mean ages at arrest of East German prisoners with chronic PTSD and remitted PTSD.
> D. Cristol et al. published results of their studies of two subspecies of dark-eyed juncos in the article “Migratory Dark-Eyed Juncos, Junco Hyemalis, Have Better Spatial Memory and Denser Hippocampal Neurons than Nonmigratory Conspecifics” (Animal Behav
> Previous research has suggested that changes in the activity of dopamine, a neurotransmitter in the brain, may be a causative factor for schizophrenia. In the paper “Schizophrenia: Dopamine β-Hydroxylase Activity and Treatment Response” (Science, Vol. 21
> An intervention program designed by the Stockholm Transit District was implemented to improve the work conditions of the city’s bus drivers. Improvements were evaluated by G. Evans et al., who collected physiological and psychological data for bus driver
> The researchers also obtained the following data on the number of acute postoperative days in the hospital using the dynamic and static systems. At the 5% significance level, does the data provide sufficient evidence to conclude that the mean number of a
> Phyllodes tumors of the breast are rare tumors that represent less than one percent of growths in the breast. Researchers I. Youn et al. presented characteristics of phyllodes tumors in the article “Phyllodes Tumors of the Breast: Ultrasonographic Findin
> According to the American Psychiatric Association, posttraumatic stress disorder (PTSD) is a common psychological consequence of traumatic events that involve a threat to life or physical integrity. During the Cold War, some 200,000 people in East German
> We have provided summary statistics for independent simple random samples from two populations. In each case, use the non-pooled t-test and the non-pooled t-interval procedure to conduct the required hypothesis test and obtain the specified confidence in
> The primary concern is deciding whether the mean of Population 2 is greater than the mean of Population 1. a. Determine the null and alternative hypotheses. b. Classify the hypothesis test as two tailed, left tailed, or right tailed.
> We have provided summary statistics for independent simple random samples from two populations. In each case, use the non-pooled t-test and the non-pooled t-interval procedure to conduct the required hypothesis test and obtain the specified confidence in
> The Bureau of Economic Analysis gathers information on the length of stay in Europe and the Mediterranean by U.S. travelers. Data are published in Survey of Current Business. The following stem-and-leaf diagram portrays the length of stay, in days, of a
> We have provided summary statistics for independent simple random samples from two populations. In each case, use the non-pooled t-test and the non-pooled t-interval procedure to conduct the required hypothesis test and obtain the specified confidence in
> We have provided summary statistics for independent simple random samples from two populations. In each case, use the non-pooled t-test and the non-pooled t-interval procedure to conduct the required hypothesis test and obtain the specified confidence in
> We have provided summary statistics for independent simple random samples from two populations. In each case, use the non-pooled t-test and the non-pooled t-interval procedure to conduct the required hypothesis test and obtain the specified confidence in
> We have provided summary statistics for independent simple random samples from two populations. In each case, use the non-pooled t-test and the non-pooled t-interval procedure to conduct the required hypothesis test and obtain the specified confidence in
> Discuss the relative advantages and disadvantages of using pooled and non-pooled t-procedures.
> Each pair of graphs in Fig. 10.8 shows the distributions of a variable on two populations. Suppose that, in each case, you want to perform a small-sample hypothesis test based on independent simple random samples to compare the means of the two populatio
> suppose that you know that a variable is normally distributed on each of two populations. Further suppose that you want to perform a hypothesis test based on independent random samples to compare the two population means. Decide whether you would use the
> suppose that you know that a variable is normally distributed on each of two populations. Further suppose that you want to perform a hypothesis test based on independent random samples to compare the two population means. Decide whether you would use the
> suppose that you know that a variable is normally distributed on each of two populations. Further suppose that you want to perform a hypothesis test based on independent random samples to compare the two population means. Decide whether you would use the
> The primary concern is deciding whether the mean of Population 1 is greater than the mean of Population 2. a. Determine the null and alternative hypotheses. b. Classify the hypothesis test as two tailed, left tailed, or right tailed.
> A study published by E. Anionwu et al. in the British Medical Journal (Vol. 282, pp. 283–286) measured the steady-state hemoglobin levels of patients with three different types of sickle cell disease. Following is a stem-and-leaf diagram of the data.
> suppose that you know that a variable is normally distributed on each of two populations. Further suppose that you want to perform a hypothesis test based on independent random samples to compare the two population means. Decide whether you would use the
> Suppose that you want to perform a hypothesis test to compare the means of two populations, using independent simple random samples. Assume that the two distributions of the variable under consideration have the same shape, but are not normal, and both s
> Suppose that you want to perform a hypothesis test to compare the means of two populations, using independent simple random samples. Assume that the two distributions (one for each population) of the variable under consideration are normally distributed
> If the assumptions for a pooled t-interval are satisfied, the formula for a (1 − α)-level lower confidence bound for the difference, μ1 − μ2, between two population means is For a right-tailed hypothesis test at the significance level α, the null hypothe
> If the assumptions for a pooled t-interval are satisfied, the formula for a (1 − α)-level upper confidence bound for the difference, μ1 − μ2, between two population means is For a left-tailed hypothesis test at the significance level α, the null hypothes
