In the article “Assessment of Dermatopharmacokinetic Approach in the Bioequivalence Determination of Topical Tretinoin Gel Products” (L. Pershing, J. Nelson, et al., Journal of the American Academy of Dermatology, 2003:740–751), measurements of the concentration of an anti-fungal gel, in ng per square centimeter of skin, were made one hour after application for 49 individuals. Following are the results. The authors claim that these data are well-modeled by a lognormal distribution. Construct an appropriate
132.44 76.73 258.46 177.46 73.01 130.62 235.63
107.54 75.95 70.37 88.76 104.00 19.07 174.30
82.87 68.73 41.47 120.44 136.52 82.46 67.04
96.92 93.26 72.92 138.15 82.43 245.41 104.68
82.53 122.59 147.12 129.82 54.83 65.82 75.24
135.52 132.21 85.63 135.79 65.98 349.71 77.84
89.19 102.94 166.11 168.76 155.20 44.35 202.51
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Statistics for Engineers and Scientists
- A study was conducted to examine the effect of diet cola consumption on calcium levels in women. A sample of 16 healthy women aged 18 to 40 were randomly assigned to drink 24 ounces of either diet cola or water. Their urine was collected for three hours after ingestion of the beverage and calcium excretion (in mg) was measured. The data are stored in ColaCalcium.arrow_forwardA sample of 10 diesel trucks were run both hot and cold to estimate the difference in fuel economy. The results, in mpg. are presented in the following table. (From "In-use Emissions from Heavy-Duty Diesel Vehicles," J. Yanowitz, Ph.D. thesis, Colorado School of Mines, 2001.) Truck Hot Cold 4.56 4.26 2 4.46 4.08 3 6.49 5.83 5.37 4.96 5 6.25 5.87 6 5.90 5.32 4.12 3.92 8 3.85 3.69 4.15 3.74 10 4.69 4.19 Find a 98% confidence interval for the difference in mean fuel mileage between hot and cold engines.arrow_forwardThe article “Wastewater Treatment Sludge as a Raw Material for the Production of Bacillus thuringiensis Based Biopesticides” (M. Tirado Montiel, R. Tyagi, and J. Valero, Water Research, 2001:3807–3816) presents measurements of total solids, in g/L, for seven sludge specimens. The results (rounded to the nearest gram) are 20, 5, 25, 43, 24, 21, and 32. Assume the distribution of total solids is approximately symmetric. a) Can you conclude that the mean concentration of total solids is greater than 14 g/L? Compute the appropriate test statistic and find the P-value. b) Can you conclude that the mean concentration of total solids is less than 30 g/L? Compute the appropriate test statistic and find the P-value. c) An environmental engineer claims that the mean concentration of total solids is equal to 18 g/L. Can you conclude that the claim is false?arrow_forward
- In experiments to determine the effectiveness of drugs such as anti-fungal ointments that are applied to the skin, the concentration of the drug in a patient’s skin must be measured. The article “Determining Bioequivalence of Topical Dermatological Drug Products by Tape- Stripping” (W. Navidi, A. Hutchinson, et al., Journal of Pharmacokinetics and Pharmacodynamics, 2008:213–220) describes an improved method of measuring that is designed to ensure that all the drug in the skin is recovered. Assume that in an experiment using the old method, the mean amount of drug recovered from a sample of 49 patients was 105 ng with a standard deviation of 20 ng, and that in an experiment using the new method the mean amount of drug recovered in a sample of 35 patients was 117 ng with a standard deviation of 15 ng. Find a 98% confidence interval for the difference in the mean amounts recovered between the two methods.arrow_forwardThe depth of wetting of a soil is the depth to which water content will increase owing to extemal factors. The article "Discussion of Method for Evaluation of Depth of Wetting in Residential Areas" (J. Nelson, K. Chao, and D. Overton, Journal of Geotechnical and Geoenvironmental Engineering, 2011:293-296) discusses the relationship between depth of wetting beneath a structure and the age of the structure. The article presents measurements of depth of wetting, in meters, and the ages, in years, of 21 houses, as shown in the following table. Age Depth 7.6 4 4.6 6.1 9.1 3 4.3 7.3 5.2 10.4 15.5 5.8 10.7 4 5.5 6.1 10.7 10.4 4.6 7.0 6.1 14 16.8 10 9.1 8.8 Compute the least-squares line for predicting depth of wetting (y) from age (x). b. Identify a point with an unusually large x-value. Compute the least-squares line that results from deletion of this point. Identify another point which can be classified as an outlier. Compute the least-squares line that results from deletion of the outlier,…arrow_forwardThe cetane number is a critical property in specifying the ignition quality of a fuel used in a diesel engine. Determination of this number for a biodiesel fuel is expensive and time- consuming. The article "Relating the Cetane Number of Biodiesel Fuels to Their Fatty Acid Composition: A Critical Study" (J. of Automobile Engr., 2009: 565–583) included the following data on x = iodine value (g) and y = cetane number for a sample of 15 biofuels The iodine value (x) is the amount of iodine necessary to saturate a sample of 100 g of oil. The article's authors fit the simple linear regression model to this data, so let' s does the same. 132.0 129.0 120.0 113.2 105.0 92.0 84.0 88.4 59.0 80.0 81.0 81.5 71.0 69.2 63.0 y 46.0 48.0 51.0 52.1 54.0 52.0 59.0 58.7 61.6 64.0 61.4 54.6 58.8 58.0 51.4 3) Estimate the correlation coefficient (Pearson coefficient), r, between x and y and explain briefly the strength of r and its direction and comment the p-value. 4) Construct a 95% two-sided confidence…arrow_forward
- The cetane number is a critical property in specifying the ignition quality of a fuel used in a diesel engine. Determination of this number for a biodiesel fuel is expensive and time- consuming. The article "Relating the Cetane Number of Biodiesel Fuels to Their Fatty Acid Composition: A Critical Study" (J. of Automobile Engr., 2009: 565–583) included the following data on x = iodine value (g) and y = cetane number for a sample of 15 biofuels The iodine value (x) is the amount of iodine necessary to saturate a sample of 100 g of oil. The article's authors fit the simple linear regression model to this data, so let' s does the same. 132.0 129.0 120.0 113.2 105.0 92.0 84.0 88.4 59.0 80.0 81.0 81.5 71.0 69.2 63.0 y 46.0 48.0 51.0 52.1 54.0 52.0 59.0 58.7 61.6 64.0 61.4 54.6 58.8 58.0 51.4 Construct a scatter plot for the data. Identify and state which is dependent and independent variable. What is the purpose of the scatter plot/diagram? 2. Fit a simple linear regression line/ equation to…arrow_forwardAn article in the Journal of Environmental Engineering (1989, Vol. 115(3), pp. 608–619) reported the results of a study on the occurrence of sodium and chloride in surface streams in central Rhode Island. The following data are chloride concentration y (in milligrams per liter) and roadway area in the watershed x (in percentage).arrow_forwardCaptopril 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_forward
- The background concentration of a chemical in soil was measured on ten random specimens of soil from an uncontaminated area. The measured concentrations, in mg/kg, are: 1.4, 0.6, 1.2, 1.6, 0.5, 0.7, 0.3, 0.8, 0.2, and 0.9. Soil from a neighboring area will be declared “contaminated” if test specimens contain a chemical concentration higher than the upper 99% confidence limit of the background level. What is the cleanup target concentration?arrow_forwardAdding glass particles to clay brick may improve the structural properties of the brick. The article "Effects of Waste Glass Additions on the Properties and Durability of Fired Clay Brick" (S. Chidiac and L. Federico, Can J Civ Eng, 2007:1458–1466) describes experiments in which the compressive strength (in MPa) was measured for bricks with varying amounts of glass content and glass particle size. The results in the following table are consistent with means and standard deviations presented in the article. Glass Content (%) Strength (MPa) Size 5 Coarse 78.7 70.8 78.6 81.7 79.2 5 Fine 73.0 90.1 71.4 93.8 82.7 10 Coarse 80.1 76.9 76.5 84.3 77.7 10 Fine 76.2 80.1 121.2 81.4 61.2 15 Coarse 90.3 95.8 103.1 99.5 73.3 15 Fine 141.1 144.1 122.4 134.5 124.9 a. Estimate all main effects and interactions. b. Construct an ANOVA table. You may give ranges for the P-values. Is the additive model plausible? Provide the value of a test statistic and the P-value. Can the effect of glass content on…arrow_forwardA study was conducted to compare three methods of measuring concentration of certain type of chemical pollutants in a lake. The data is given in Table 1 below. Compute SS(between) and SS(within). Compute SS(total), and explain the relationship between SS(between), SS(within), and SS(total). Compute MS(between), MS(within), and F statistic. Based on your computations, are there significant differences in the mean pollutant concentrations among the three methods?Table 1. Amount of concentration of a chemical pollutant in a lake using three different measuring methods Method 1 Method 2 Method 3 10.96 10.88 10.73 10.77 10.75 10.79 10.90 10.80 10.78 10.69 10.81 10.82 10.87 10.70 10.88 10.6 10.82 10.81arrow_forward
- Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill