Concept explainers
Compared to their stay-at-home peers, women employed outside the home have higher levels of high-density lipoproteins (HDL), the “good” cholesterol associated with lower risk for heart attacks. A study of cholesterol levels in 2000 women, aged 25–64, living in Augsburg, Germany, was conducted by Ursula Haertel, Ulrigh Keil, and colleagues2 at the GSF-Medis Institut in Munich. Of these 2000 women, the 48% who worked outside the home had HDL levels that were between 2.5 and 3.6 milligrams per deciliter (mg/dL) higher than the HDL levels of their stay-at-home counterparts. Suppose that the difference in HDL levels is
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Chapter 1 Solutions
Mathematical Statistics with Applications
- Research done at the Harvard School of Public Health showed that regular soda drinkers may have a tendency toward the weak and brittle bones associated with osteoporosis. They surveyed 2,622 women who were active athletes in college and classified them as to whether they regularly drank soft drinks or rarely drank soft drinks. The proportion of women in each group who suffered from bone fractures was determined. The findings: those who regularly drank soft drinks were twice as likely to suffer from bone fractures as those who rarely drank soft drinks. Source: Health and Fitness News Service, August 21, 1996. a. Was this an observational study or an experiment? Explain.b. What is the population under study?c. What was the explanatory variable?d. What was the response variable?e. What are some possible confounding variables in this study?arrow_forwardResearch done at the Harvard School of Public Health showed that regular soda drinkers may have a tendency toward the weak and brittle bones associated with osteoporosis. They surveyed 2,622 women who were active athletes in college and classified them as to whether they regularly drank soft drinks or rarely drank soft drinks. The proportion of women ineach group who suffered from bone fractures was determined. The findings: those who regularly drank soft drinks were twice as likely to suffer from bone fractures as those who rarely drank soft drinks. Source: Health and Fitness News Service, August 21, 1996. What was the response variable? What are some possible confounding variables in this study?arrow_forwardIn clinical trails of Nasonex, 3774 adult and adolenscent allergy patients 12 years and older were randomly divided into two groups. The patient in group1 (experimental group) received 200 microgram of Nasonex, while the patient in group 2( control group) receiced a placebo. Of the 2103 patients in the experimental group 547 reported headaches as a side effect. Of the 1671 patients in the control group, 368 reported headaches as a side effect. Determine if the proportion of those taking Nasonex who experienced headaches as a side effect differs from that of those taking the placebo who experienced headaches as a side effect. A) state the null and alternative hypothese: B) construct a 95% confidence interval for the difference between these groups round to 4 places. Intervals: C)using intervals, state conclusion in the language of the problem.arrow_forward
- A consumer advocacy group wanted to study whether different airline carriers differed in terms of their delayed flights. In particular, the researchers were interested in the relationship between p1, the proportion of Alpha Airlines flights that were delayed at least 15 minutes, and p2, the proportion of Beta Airlines flights that were delayed at least 15 minutes. A random sample of 1,000 Alpha flights and a separate random sample of 1,000 Beta flights found that 67 of the Alpha fights and 160 of the Beta flights were delayed at least 15 minutes. The conditions for inference were checked and verified. Does this set of samples provide strong evidence that Alpha Airlines has a smaller proportion of flights that are delayed at least 15 minutes than Beta Airlines, at the α = 0.05 significance level? Find the z-table here. A. The test statistic is z = –6.56 and the P-value ≈ 0. Since the P-value ≈ 0 < 0.05, there is not sufficient evidence that Alpha Airlines has fewer delayed…arrow_forwardWertheretal et al. examined the β-leucocyte count (/ L) in 51subjects with colorectal cancer and 19 healthy controls. The cancer patients were also classified into Dukes’s classification (A,B,C) for colorectal cancer that gives doctors a guide to the risk, following surgery, of cancer coming back or spreading to other parts of the body. An additional category (D) identified patients with disease that had not been completely resected. The results are displayed in the following table. Perform an analysis of these data in which you identify the sources of variability and specify the degrees of freedom for each. Do these data provide sufficient evidence to indicate that, on average, leucocyte counts differ among the five categories? Let α=0.01 . Write the null and alternative hypotheses of this study. Test the claim using the ANOVA Table. If you reject the null hypothesis, interpret your results using multiple comparison test Bonferroni. What assumptions must be made in part (b)? Are they…arrow_forwardIn 1992, the U.S. Public Health Service and the Centres for Disease Control and Prevention recommended that all women of childbearing age consume 400mg of folic acid daily to reduce the risk of having a pregnancy that is affected by a neural tube defect such as spina bifida or anencephaly. In a study by Stepanuk et al. (A-3), 693 pregnant women called a teratology information service about their use of folic acid supplementation. The researchers wished to determine if preconceptional use of folic acid and race are independent. The data appear in Table below: Total Preconceptional Use of Folic Acid Race No Yes 559 299 260 White 56 41 15 Black 21 14 7 Other 636 354 282 Total Test the hypothesis that there is no association between the usage of folic acid and race with 5% significant level and using SPSS (Choose only 4 correct answers from the following statements): 1. The null and alternative hypothesis are: H0: The two variables are dependent. H1: The two…arrow_forward
- A large randomized trial was conducted to assess the efficacy of Chantix for smoking cessation compared with bupropion (more commonly known as Wellbutrin or Zyban) and a placebo. Chantix is different from most other quit‑smoking products in that it targets nicotine receptors in the brain, attaches to them, and blocks nicotine from reaching them, while bupropion is an antidepressant often used to help people stop smoking. Generally healthy smokers who smoked at least 1010 cigarettes per day were assigned at random to take Chantix ( ?=352n=352 ), bupropion ( ?=329n=329 ), or a placebo ( ?=344n=344 ). The response measure is continuous cessation from smoking for Weeks 99 through 1212 of the study. A two‑way table of the results is given. Treatment Chantix Bupropion Placebo No smoke in weeks 9-12 155 97 61 Smokes in weeks 9-12 197 232…arrow_forwardA heart study objective was to study heart disease among healthy volunteers.After a 10-year follow-up period involving men aged 40 to 59, there were 16 casesof coronary heart disease (CHD) among the 454 men who initially had cholesterollevels below 210 mg/100 ml (referred to as the low serum cholesterol group). Incontrast, among the 424 men whose initial cholesterol levels were at least 245mg/100 ml (referred to as the high serum cholesterol group), there were 51 cases ofCHD. With this information, Draw a 2x2 contingency table then calculate the relative risk (RR) associated with high serum cholesterol and provide an interpretation of the result.arrow_forwardChocolate contains caffeine and an endogenous cannabinoid, as well as a chemical thatmodulates serotonin production; but is it an aphrodisiac, as the Mayans and Aztecs believed?Suppose you conduct a study which measures sex drive in a group of 20 women, after eating 8ounces of chocolate. Given that you have available data from the Kinsey Institute (IndianaUniversity) about the general sex drive for women of the same demographic as in your study, youdecide to compare your group to this population estimate.If testing hypotheses about the effects of chocolate on sex drive, it would be most appropriate tocalculate a ...1)Paired sampled t2)Z-test3)Independent-samples t-test 4)One- sample t-testarrow_forward
- The Joint Commission on Accreditation of Healthcare Organizations mandated that hospitals ban smoking by 1994. To study the effects of this ban on smoking behaviors, subjects were randomly selected from two different populations: those from hospitals with the ban and those from hospitals without the ban. Investigators were interested in determining if this smoking ban had any impact on the proportion of smokers employed at each hospital that then quit smoking. Let px be the proportion of smokers from hospitals that implemented the ban who quit smoking during the study period. Let py be the proportions of smokers from hospitals without the ban who quit smoking during the study period. Please select the appropriate hypotheses. H0: px = 0.50 HA: px ≠ 0.50 H0: px-py ≥ 0 HA: px-py H0: px-py ≤ 0 HA: px-py > 0 H0: px-py = 0 HA: px-py ≠ 0arrow_forwardA randomized study was performed to determine whether a diet of processed meats causes a higher proportion of incidents of breast cancer. Researchers compared high intake versus low intake diets of processed meats for women with breast cancer and found the following results shown in the two-way table below: Breast Cancer No Breast Cancer Total High Intake processed meat 93 157 250 Low Intake processed meat 67 163 230 Conduct a hypothesis test for this problem, using for the proportion with diet high in processed meat who got breast cancer and for the proportion of women with diet low in processed meat who got breast cancer. PLEASE HELP WITH THE FOLLOWING - Find the p-value. Write generic conclusion. Write conclusion in context.arrow_forwardA recent report states that 55% of U.S. adults use Netflix to stream shows and movies. An advertising company believes the proportion of California residents who use Netflix is greater than the national proportion, because Netflix headquarters is located in Los Gatos, California. The company selects a random sample of 600 adults from California and finds that 360 of them use Netflix. Is there convincing evidence at the alpha = .05 level that more than 55% of California residents use Netflix?arrow_forward
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