Concept explainers
The article “Drift in Posturography Systems Equipped with a Piezoelectric Force Platform: Analysis and Numerical Compensation” (L. Quagliarella, N. Sasanelli, and V. Monaco, IEEE Transactions on Instrumentation and Measurement, 2008:997–1004) reported the results of an experiment to determine the effect of load on the drift in signals derived from a piezoelectric force plate. The
x | y |
0.196 | –0.9710 |
0.245 | –0.9735 |
0.294 | –0.9694 |
0.343 | –0.9684 |
0.392 | –0.9624 |
0.441 | –0.9688 |
0.490 | –0.9519 |
0.539 | –0.9573 |
0.588 | –0.9515 |
- a. Compute the least-squares line for predicting y from x.
- b. Plot the residuals versus the fitted values. Does the least-squares line seem appropriate?
- c. Compute the least-squares line for predicting y from x2.
- d. Plot the residuals versus the fitted values. Does the least-squares line seem appropriate?
- e. For each model, find a 95% confidence interval for the
mean value of y when x = 0.32. Are the confidence intervals similar?
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- In the article “Groundwater Electromagnetic Imaging in Complex Geological and Topographical Regions: A Case Study of a Tectonic Boundary in the French Alps” (S. Houtot, P. Tarits, et al., Geophysics, 2002:1048–1060), the pH was measured for several water samples in various locations near Gittaz Lake in the French Alps. The results for 11 locations on the northern side of the lake and for 6 locations on the southern side are as follows: Northern side: 8.1 8.2 8.1 8.2 8.2 7.4 7.3 7.4 8.1 8.1 7.9 Southern side: 7.8 8.2 7.9 7.9 8.1 8.1 Find a 98% confidence interval for the difference in pH between the northern and southern side.arrow_forwardThe article “Hydrogeochemical Characteristics of Groundwater in a Mid-Western CoastalAquifer System” (S. Jeen, J. Kim, et al., Geosciences Journal, 2001:339–348) presentsmeasurements of various properties of shallow groundwater in a certain aquifer system inKorea. Following are measurements of electrical conductivity (in microsiemens percentimeter) for 23 water samples.2099 528 2030 1350 1018 384 14991265 375 424 789 810 522 513488 200 215 486 257 557 260461 500Find the mean.Find the standard deviation.Find the median.Construct a dotplot.Find the 10% trimmed mean.Find the first quartile.Find the third quartile.Find the interquartile range.Construct a boxplot.Which of the points, if any, are outliers?If a histogram were constructed, would it be skewed to the left, skewed to the right, orapproximately symmetric?arrow_forwardFollowing are the protein contents measured in two types of species:Species 1: 0.72 1.12 0.81 0.89 0.72 0.81 1.01 0.75 0.83Species 2: 1.21 0.93 0.80 1.12 1.22 0.94 0.87 i) Assuming normality, test the hypothesis that the two species have the sameaverage protein contents by using 5-step hypothesis testing procedure at 5 %level of significance, and using the critical values approach.ii) Calculate the p-value of this test and make decision.iii) Write down the standard error of this test and calculate its numerical value ?arrow_forward
- An urban community wants to show that the incidence of breast cancer is higher in their locality than in a neighboring rural area. (PCB levels were found to be higher in the soil of the urban community). If you find that in the urban community 20 out of 200 adult women have breast cancer and that in the rural community 10 out of 150 adult women have it, could you conclude, at a significance level of 0.05, that breast cancer is more prevalent in the urban community?1. The parameter of interest is:2. The hypotheses for this test are:3. The calculated test statistic is:4. The critical region is:5. Draw the critical region (make decision):6. It can be concluded that:arrow_forwardThe article “Differences in Susceptibilities of Different Cell Lines to Bilirubin Damage” (K. Ngai, C. Yeung, and C. Leung, Journal of Paediatric Child Health, 2000:36–45) reports an investigation into the toxicity of bilirubin on several cell lines. Ten sets of human liver cells and 10 sets of mouse fibroblast cells were placed into solutions of bilirubin in albumin with a 1.4 bilirubin/albumin molar ratio for 24 hours. In the 10 sets of human liver cells, the average percentage of cells surviving was 53.9 with a standard deviation of 10.7. In the 10 sets of mouse fibroblast cells, the average percentage of cells surviving was 73.1 with a standard deviation of 9.1. Find a 98% confidence interval for the difference in survival percentages between the two cell lines.arrow_forward19. An article in International Journal of Electrical Power & Energy Systems "Stochastic Optimal Load Flow Using a Combined Quasi-Newton and Conjugate Gradient Technique" (1989, Vol. 11(2), pp. 85-93) considered the problem of optimal power flow in electric power systems and included the effects of uncertain variables in the problem formulation. The method treats the system power demand as a normal random variable with 0 mean and unit variance. What is the probability that the power demand is greater than -2 and less than 2? Round your answer to three decimal places (e.g. 98.765).arrow_forward
- Lactation promotes a temporary loss of bone mass to provide adequate amounts of calcium for milk production. The paper “Bone Mass Is Recovered from Lactation to Postweaning in Adolescent Mothers with Low Calcium Intakes” (Amer. J. of Clinical Nutr., 2004: 1322–1326) gave the following data on total body bone mineral content (TBBMC) (g) for a sample both during lactation (L) and in the postweaning period (P). SubjectL 1928 2549 2825 1924 1628 2175 2114 2621 1843 2541P 2126 2885 2895 1942 1750 2184 2164 2626 2006 2627 Does the data suggest that true average total body bone mineral content during postweaning exceeds that during lactation by more than 25 g? State and test the appropriate hypotheses using a significance level of .05.arrow_forward14. an article in International Journal of Electrical Power & Energy Systems {"Stochastic Optimal Load Flow Using a Combined Quasi-Newton and Conjugate Gradient Technique" (1989, Vol. 11(2), pp. 85-93)} considered the problem of optimal power flow in electric power systems and included the effects of uncertain variables in the problem formulation. The method treats the system power demand as a normal random variable with 0 mean and unit variance. What is the power demand value that is exceeded with 80% probability? Round your answer to two decimal places (e.g. 98.76).arrow_forwardA golf tee manufacturer used a robot to hit balls off of their tee and a competitor's tee using the same club. Assume that 101balls were hit off each tee, and the data are suitable for inference. Is there evidence that balls hit off the manufacturer's tee have a higher initial velocity? (Assume a significance level of 0.05.) Distance (yards) Distance (yards) Ball Velocity (mph) Ball Velocity (mph) Club Velocity (mph) Club Velocity (mph) Avg. SD Avg. SD Avg. SD Competition 220.05 2.02 124.11 0.85 90.82 0.44 Manufacturer 222.28 2.57 125.37 0.41 90.82 0.44 a) Compute the t-statistic. t=_____ (Round to three decimal places as needed.) b)Compute the P-Value P-Value=_____ (Round to three decimal places as needed.)arrow_forward
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