In Exercises 1.17–1.22, state whether the investigation in question is an observational study or a designed experiment. Justify your answer in each case.
Heart Failure. In the paper “Cardiac-Resynchronization Therapy with or without an Implantable Defibrillator in Advanced Chronic Heart Failure” (New England Journal of Medicine, Vol. 350, pp. 2140–2150), M. Bristow et al. reported the results of a study of methods for treating patients who had advanced heart failure due to ischemic or nonischemic cardiomyopathies. A total of 1520 patients were randomly assigned in a 1:2:2 ratio to receive optimal pharmacologic therapy alone or in combination with either a pacemaker or a pacemaker–defibrillator combination. The patients were then observed until they died or were hospitalized for any cause.
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- A local church is interested in determining how length of residence in the present community relates to church attendance. Using a random sample of 15 individuals, they gathered data on how many times in the previous 5 weeks each individual attended church services. The data are provided below. Length of residence in the community Less than 2 years 2-5 years More than 5 years 0 0 1 1 2 3 3 3 3 4 4 4 4 5 4 Using the 5-step model, determine whether and how church attendance is related to length of residence in the community. Use 5% and 1% levels of statistical significance. What are the assumptions for this problem?arrow_forwardResearchers interested in lead exposure due to car exhaust sampled the blood of 52 police officers subjected to constant inhalation of automobile exhaust fumes while working traffic enforcement in a primarily urban environment. The blood samples of these officers had an average lead concentration of 124.32 µg/l and a SD of 37.74 µg/l; a previous study of individuals from a nearby suburb, with no history of exposure, found an average blood level concentration of 35 µg/l. Test the hypothesis that the downtown police officers have a higher lead exposure than the group in the previous study. Interpret your results in context. Based on your preceding result, without performing a calculation, would a 99% confidence interval for the average blood concentration level of police officers contain 35 µg/l? Based on your preceding result, without performing a calculation, would a 99% confidence interval for this difference contain 0? Explain why or why not.arrow_forwardIn terms of the model parameters, state the null hypothesis that, after controlling for sales and roe, ros has no effect on CEO salary. State the alternative that better stock market performance increases a CEO’s salary.arrow_forward
- b) What are the three models proposed as extensions of the GARCH model? Describe their advantages over the GARCH.arrow_forwardIn a study of exhaust emissions from school buses, the pollution intake by passengers was determined for a sample of nine school buses used in the Southern California Air Basin. The pollution intake is the amount of exhaust emissions, in grams per person per million grams emitted, that would be inhaled while traveling on the bus during its usual 18-mile18-mile trip on congested freeways from South Central LA to a magnet school in West LA. (In comparison, a city of 11 million people will inhale a total of about 1212 grams of exhaust per million grams emitted.) The amounts for the nine buses when driven with the windows open are given in the table. 1.15 0.33 0.40 0.33 1.35 0.38 0.25 0.40 0.35 A good way to judge the effect of outliers is to do your analysis twice, once with the outliers and a second time without them. Give the 90%90% confidence interval with all the data for the mean pollution intake among all school buses used in the Southern California Air Basin that…arrow_forwardIn the book Business Research Methods (5th ed.), Donald R. Cooper and C. William Emory discuss studying the relationship between on-the-job accidents and smoking. Cooper and Emory describe the study as follows: Suppose a manager implementing a smoke-free workplace policy is interested in whether smoking affects worker accidents. Since the company has complete reports of on-the-job accidents, she draws a sample of names of workers who were involved in accidents during the last year. A similar sample from among workers who had no reported accidents in the last year is drawn. She interviews members of both groups to determine if they are smokers or not. The sample results are given in the following table. On-the-Job Accident Smoker Yes No Row Total Heavy 12 5 17 Moderate 9 10 19 Nonsmoker 13 17 30 Column total 34 32 66 Expected counts are below observed counts Accident No Accident Total Heavy 12 5 17 8.76 8.24…arrow_forward
- In a study attempting to replicate findings by Stephens, Atkins, & Kingston (2009), each participant was asked to plunge a hand into the icy water and keep it there as long as the pain would allow. In one condition, the participants repeated their favorite curse words while their hands were in the water. In the other condition, they repeated neutral words. The original research showed that, in addition to lowering the participants’ perception of pain, swearing also increased the amount of time they were able to tolerate the pain. Data similar to the results obtained in the study are shown in the following table: _____________Amount of Time (in Seconds)_ Participant Swear Words Neutral Words 1 94 59 2 70 61 3 52 47 4…arrow_forwardIn a study attempting to replicate findings by Stephens, Atkins, & Kingston (2009), each participant was asked to plunge a hand into the icy water and keep it there as long as the pain would allow. In one condition, the participants repeated their favorite curse words while their hands were in the water. In the other condition, they repeated neutral words. The original research showed that, in addition to lowering the participants’ perception of pain, swearing also increased the amount of time they were able to tolerate the pain. Data similar to the results obtained in the study are shown in the following table: _____________Amount of Time (in Seconds)_ Participant Swear Words Neutral Words 1 94 59 2 70 61 3 52 47 4…arrow_forwardSecond-Hand Smoke: Data Set 12 “Passive and Active Smoke” in Appendix B includes cotinine levels measured in a group of nonsmokers exposed to tobacco smoke (n = 40, Mean = 60.58 ng>mL, s = 138.08 ng>mL) and a group of nonsmokers not exposed to tobacco smoke (n = 40, Mean = 16.35 ng>mL, s = 62.53 ng>mL). Cotinine is a metabolite of nicotine, meaning that when nicotine is absorbed by the body, cotinine is produced. Use a 0.05 significance level to test the claim that nonsmokers exposed to tobacco smoke have a higher mean cotinine level than nonsmokers not exposed to tobacco smoke. Construct the confidence interval appropriate for the hypothesis test in part a. What do you conclude about the effects of second-hand smoke?arrow_forward
- Explain the Stationarity in the AR(1) Model?arrow_forwardA doctor would like to evaluate whether flu-frequency is different among patients of various ages. He groups his most recent 12 patients into four groups according to age (pediatric, young adult, older adult, senior), and counts the frequency of their flu-related visits. Below is his data. Test the hypothesis that flu frequency is different among pediatric, adult, older adult, and senior patients using an alpha level of .01. Pediatric. Young Adult. Older Adult. Senior 6 2 4 7 4 1 0 9 5 0 0 12 d. Find the critical value: e. Calculate the obtained statistic: f. Make a decision: g. What does your decision mean? h.…arrow_forwardWindy, part III Exercises 12 and 14 give summaries anddisplays for two potential sites for a wind turbine. Testan appropriate hypothesis to see if there is evidence thateither of these sites has a higher average wind speed.arrow_forward
- Big Ideas Math A Bridge To Success Algebra 1: Stu...AlgebraISBN:9781680331141Author:HOUGHTON MIFFLIN HARCOURTPublisher:Houghton Mifflin Harcourt