A blood lead level of 70 mg/ml has been commonly accepted as safe. However, researchers have noted that some neurophysiological symptoms of lead poisoning appear in people whose blood lead levels are below 70 mg/ml. The article “Subclinical Neuropathy at Safe Levels of Lead Exposure” (Archives of Environmental Health [1975]: 180–183) gave the following nerve-conduction velocities for a group of workers who were exposed to lead in the workplace but whose blood lead levels were below 70 mg/ml and for a group of controls who had no exposure to lead:
Use a level 0.05 rank-sum test to determine whether there is a significant difference in mean conduction velocity between workers exposed to lead and those not exposed to lead.
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- Captopril is a drug designed to lower systolic blood pressure. When subjects were treated with this drug, their systolic blood pressure readings (in mm Hg) were measured before and after the drug was taken. Results are given in the accompanying table (based on data from “Essential Hypertension: Effect of an Oral Inhibitor of Angiotensin-Converting Enzyme”, by MacGregor et al., BMJ, Vol. 2). Using a 0.01 significance level, is there sufficient evidence to support the claim that captopril has an effect on systolic blood pressure? i) Use the Wilcoxon signed-ranks test to conduct the required test without using "wilcox.test" function in R. Please state the hypothesis, provide the p-value, and the conclusion in the context of the problem. ii) Use the Wilcoxon signed-ranks test to conduct the required test using "wilcox.test" function in R. Please present a screenshot of the R output of your call to the function wilcox.test. iii) Would you recommend the Wilcoxon signed-ranks test over the…arrow_forward1. Captopril is a drug designed to lower systolic blood pressure. When subjects were treated with this drug, their systolic blood pressure readings (in mm Hg) were measured before and after the drug was taken. Results are given in the accompanying tables (based on data from "Essential Hypertension: Effect of an Oral Inhibitor of Angiotensin-Converting Enzyme," by MacGregor et al., British Medical Journal, Vol. 2). Using a 0.01 significance level, is there sufficient evidence to support the claim that captopril is effective in lowering systolic blood pressure? Subject Before (x) 200 After (y) А В C D E F G H I K 174 198 170 179 182 193 209 185 155 169 210 191 170 177 167 159 151 176 183 159 145 146 177 2. A study was conducted to investigate the effectiveness for randomly selected subjects are given in the accompanying table (based on "An Analysis of hypnotism in reducing pain. Results Factors That Contribute to the Efficacy of Hypnotic Analgesia," by Price and Barber, Journal of…arrow_forwardYoung Adults at Risk. Research by R. Pyhala et al. shows that young adults who were born prematurely with very low birth weights (below 1500 grams) have higher blood pressure than those born at term. The study can be found in the article, “Blood Pressure Responses to Physiological Stress in Young Adults with Very Low Birth Weight” (Pediatrics, Vol. 123, No. 2, pp. 731–734). The researchers found that systolic blood pressures of young adults who were born prematurely with very low birth weights have mean 120.7 mm Hg and standard deviation 13.8 mm Hg. a. Identify the population and variable. b. For samples of 30 young adults who were born prematurely with very low birth weights, find the mean and standard deviation of all possible sample mean systolic blood pressures. Interpret your results in words. c. Repeat part (b) for samples of size 90.arrow_forward
- The article "Modeling of Urban Area Stop-and-Go Traffic Noise" (P. Pamanikabud and C. Tharasawatipipat, Journal of Transportation Engineering, 1999:152–159) presents measurements of traffic noise, in dBA, from 10 locations in Bangkok, Thailand. Measurements, presented in the following table, were made at each location, in both the acceleration and deceleration lanes. Location Acceleration Deceleration 78.1 78.6 78.1 80.0 3 79.6 79.3 4 81.0 79.1 78.7 78.2 78.1 78.0 78.6 78.6 78.5 78.8 78.4 78.0 10 79.6 78.4 Can you conclude that there is a difference in the mean noise levels between acceleration and deceleration lanes?arrow_forwardHow much noisier are streets where cars travel faster? The article "Modeling of Urban Area Stop-and-Go Traffic Noise" (P. Pamanikabud and C. Tharasawatpipat, Journal of Transportation Engineering, 1999:152–159) reports noise levels in decibels and average speed in kilometers per hour for a sample of roads. The following table presents the results. Speed Noise 28.26 78.1 36.22 79.6 38.73 81.0 29.07 78.7 30.28 78.6 30.25 78.5 29.03 78.4 33.17 79.6 Compute the least-squares line for predicting noise level (y) from speed (x). b. Compute the erTor standard deviation estimate s. Construct a 95% confidence interval for the slope. Find a 95% confidence interval for the mean noise level for streets whose average speed is 30 kilometers per hour. Can you conclude that the mean noise level for streets whose average speed is 30 kilometers per hour is greater than 78 decibels? Perform a hypothesis test and report a. C. d. e. the P-value. f. Find a 95% prediction interval for the mean noise level for…arrow_forwardCONSTRUCT MODIFIED BOXPLOT To understand better the effects of exercise and aging on various cireulatory functions, the article "Cardiac Output in Male Middle-Aged Runners" (Journal of Sports Medicine [1982]: 17–22) presented data from a study of 21 middle-aged male runners. The following data set gives values of oxygen capacity values (in milliliters per kilo- gram per minute) while the participants pedaled at a speci- fied rate on a bicycle ergometer: 12.81 14.95 15.83 15.97 17.90 18.27 18.34 19.82 19.94 20.62 20.88 20.93 20.98 20.99 21.15 22.16 22.24 23.16 23.56 35.78 36.73 a. Compute the median and the quartiles for this data set. b. What is the value of the interquartile range? Are there outliers in this data set? c. Draw a modified boxplot, and comment on the interest- ing features of the plot.arrow_forward
- A cohort study is conducted to assess the association between clinical characteristics and the risk of stroke. The study involves n=1,250 participants who are free of stroke at the study start. Each participant is assessed at study start (baseline) and every year thereafter for five years. The following table displays data on hypertensive status measured at baseline and incident stroke over 5 years. Free of Stroke over 5 Years Stroke Baseline: Not Hypertensive 952 46 Baseline: Hypertensive 234 18 Compute the cumulative incidence of stroke in the study.arrow_forwardEstriol Level and Birth Weight. J. Greene and J. Touchstone conducted a study on the relationship between the estriol levels of pregnant women and the birth weights of their children. Their findings, “Urinary Tract Estriol: An Index of Placental Function,” were published in the American Journal of Obstetrics and Gynecology (Vol. 85(1), pp. 1–9). The data from the study are provided on the WeissStats site, where estriol levels are in mg/24 hr and birth weights are in hectograms. a. Decide whether finding a regression line for the data is reasonable. If so, then also do parts (b)–(d). b. Obtain the coefficient of determination. c. Determine the percentage of variation in the observed values of the response variable explained by the regression, and interpret your answer. d. State how useful the regression equation appears to be for making predictions.arrow_forwardA cohort study is conducted to assess the association between clinical characteristics and the risk of stroke. The study involves n=1,250 participants who are free of stroke at the study start. Each participant is assessed at study start (baseline) and every year thereafter for five years. The following table displays data on hypertensive status measured at baseline and incident stroke over 5 years. Free of Stroke at 5 Years Stroke Baseline: Not Hypertensive 952 46 Baseline: Hypertensive 234 18 Compute the population attributable risk of stroke for patients with hypertension.arrow_forward
- A cohort study is conducted to assess the association between clinical characteristics and the risk of stroke. The study involves n=1,250 participants who are free of stroke at the study start. Each participant is assessed at study start (baseline) and every year thereafter for five years. The following table displays data on hypertensive status measured at baseline and incident stroke over 5 years. Free of Stroke at 5 Years Stroke Baseline: Not Hypertensive 952 46 Baseline: Hypertensive 234 18 Compute the risk difference of stroke (per 5 person-years) for patients with hypertension as compared to patients free of hypertension.arrow_forwardA study published by Babcock and Marks (2010) showed that the average full-time U.S. college student studied for μ = 14 hours per week (SD = 4.8 hours per week) in 2005. We want to know if this average has changed in the past 15 years. In other words, we are going to do a study in which we try to determine whether there has been an impact of the passage of time on the amount of time college students spend studying. We selected a sample of n = 64 of today’s college students and find that they spent an average of M = 12.5 hours per week studying. Does this sample indicate a significant change in the number of hours spent studying? Use a two-tailed test (this means non-directional hypothesis) with α = .05.arrow_forward2. A case-control (or retrospective) study was conducted to investigate a relationship between the colors of helmets worn by motorcycle drivers and whether they are injured or killed in a crash. Results are given in the table below (based on data from “Motorcycle Rider Conspicuity and Crash Related Injury: Case-Control Study”, by Wells et al., BMJ USA, Vol. 4). 1. Test the claim that injuries are independent of helmet color, using chisq.test function in R at a 0.05 significance level. Please state the hypothesis, present a screenshot of the R output for this test, and provide your conclusion in the context of the problem. 2. Should motorcycle drivers choose helmets with a particular color? If so, which color appears best? Provide your justification.arrow_forward
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill