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
Want to see the full answer?
Check out a sample textbook solutionChapter 16 Solutions
Introduction to Statistics and Data Analysis
- 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_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_forwardThe article in the ASCE Journal of Energy Engineering (1999, Vol. 125, pp.59-75) describes a study of the thermal inertia properties of autoclaved aerated concrete used as a building material. Five samples of the material were tested in a structure, and the average interior temperatures (°C) reported were as follows: 23.01, 22.22, 22.04, 22.62, and 22.59. Test that the average interior temperature is equal to 22.5°C using alpha (a) = 0.05. This problem is a test on what population parameter? What is the null and alternative hypothesis? What are the Significance level and type of test? What standardized test statistic will be used? What is the standard test statistic? What is the Statistical Decision? What is the statistical decision in the statement form?arrow_forward
- 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_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_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
- How 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_forwardFoot ulcers are a common problem for people with diabetes. Higher skin temperatures on the foot indicate an increased risk of ulcers. The article "An Intelligent Insole for Diabetic Patients with the Loss of Protective Sensation" (Kimberly Anderson, M.S. Thesis, Colorado School of Mines), reports measurements of temperatures, in °F, of both feet for 181 diabetic patients. The results are presented in the following table. Left Foot Right Foot 80 80 85 85 75 80 88 86 89 87 87 82 78 78 88 89 89 90 76 81 89 86 87 82 78 78 80 81 87 82 86 85 76 80 88 89 Construct a scatterplot of the right foot temperature (y) versus the left foot temperature (x). Verify that a linear model is appropriate. b. Compute the least-squares line for predicting the right foot temperature from the left foot temperature. If the left foot temperatures of two patients differ by 2 degrees, by how much would you predict their right foot temperatures to differ? Predict the right foot temperature for a patient whose left…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 over 5 Years Stroke Baseline: Not Hypertensive 952 46 Baseline: Hypertensive 234 18 Compute the cumulative incidence of stroke in the study.arrow_forward
- Estriol 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_forwardThe size of the left upper chamber of the heart is one measure of cardiovascular health. When the upper left chamber is enlarged, the risk of heart problems is increased. The paper “Left Atrial Size Increases with Body Mass Index in Children” (International Journal of Cardiology [2009]:1-7) described a study in which the left atrial size was measured for a large number of children age 5 to 15 years. Based on this data, the authors concluded that for healthy children, left atrial diameter was approximately normally distributed with a mean of 26.4 mm and a standard deviation of 4.2 mm. Approximately what proportion of healthy children has left atrial diameters less than 24 mm? Approximately what proportion of healthy children has left atrial diameters greater than 32 mm? Approximately what proportion of healthy children has left atrial diameters between 25 and 30 mm? For healthy children, what is the value for which only about 20% have a larger left atrial diameter?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 risk difference of stroke (per 5 person-years) for patients with hypertension as compared to patients free of hypertension.arrow_forward
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill