In biofiltration of wastewater, air discharged from a treatment facility is passed through a damp porous membrane that causes contaminants to dissolve in water and be transformed into harmless products. The accompanying data on x = inlet temperature (°C) and y = removal efficiency (%) was the basis for a
Obs | Temp | Removal % | Obs | Temp | Removal % |
1 | 7.68 | 98.09 | 17 | 8.55 | 98.27 |
2 | 6.51 | 98.25 | 18 | 7.57 | 98.00 |
3 | 6.43 | 97.82 | 19 | 6.94 | 98.09 |
4 | 5.48 | 97.82 | 20 | 8.32 | 98.25 |
5 | 6.57 | 97.82 | 21 | 10.50 | 98.41 |
6 | 10.22 | 97.93 | 22 | 16.02 | 98.51 |
7 | 15.69 | 98.38 | 23 | 17.83 | 98.71 |
8 | 16.77 | 98.89 | 24 | 17.03 | 98.79 |
9 | 17.13 | 98.96 | 25 | 16.18 | 98.87 |
10 | 17.63 | 98.90 | 26 | 16.26 | 98.76 |
11 | 16.72 | 98.68 | 27 | 14.44 | 98.58 |
12 | 15.45 | 98.69 | 28 | 12.78 | 98.73 |
13 | 12.06 | 98.51 | 29 | 12.25 | 98.45 |
14 | 11.44 | 98.09 | 30 | 11.69 | 98.37 |
15 | 10.17 | 98.25 | 31 | 11.34 | 98.36 |
16 | 9.64 | 98.36 | 32 | 10.97 | 98.45 |
Calculated summary quantities are Σxi = 384.26, Σyi = 3149.04,
- a. Does a scatterplot of the data suggest appropriateness of the simple linear regression model?
- b. Fit the simple linear regression model, obtain a point prediction of removal efficiency when temperature = 10.50, and calculate the value of the corresponding residual.
- c. Roughly what is the size of a typical deviation of points in the scatterplot from the least squares line?
- d. What proportion of observed variation in removal efficiency can be attributed to the model relationship?
- e. Estimate the slope coefficient in a way that conveys information about reliability and precision, and interpret your estimate.
- f. Personal communication with the authors of the article revealed that there was one additional observation that was not included in their scatterplot: (6.53, 96.55). What impact does this additional observation have on the equation of the least squares line and the values of s and r2?
Trending nowThis is a popular solution!
Chapter 12 Solutions
Probability and Statistics for Engineering and the Sciences
- During the spring of 1999, many fuel storage facilities in Serbia were destroyed by bombing. As a result, significant quantities of oil products were spilled and burned,resulting in soil pollution. The article “Mobility of Heavy Metals Originating from Bombing of Industrial Sites” (B. Škrbić, J. Novaković, and N. Miljević, Journal of Environmental Science and Health, 2002:7–16) reports measurements of heavy metal concentrations at several industrial sites in June 1999, just after the bombing, and again in March of 2000. At the Smederevo site, on the banks of the Danube River, eight soil specimens taken in 1999 had an average lead concentration (in mg/kg) of 10.7 with a standard deviation of 3.3. Four specimens taken in 2000 had an average lead concentration of 33.8 with a standard deviation of 0.50. Find a 95% confidence interval for the increase in lead concentration between June 1999 and March 2000.arrow_forwardConsider observed data from a random sample of 390 neurons in an investigation of effect of nutritional level on brain cell growth. Test if brain cell growth is independent of nutrition levels at α= 0.05. Observed Data Poor Adequate Excellent Slow 70 95 35 Normal 90 30 70 a. At the 0.05 level of significance, the data provides sufficient evidence to conclude that cell growth is independent of nutrition. b. At the 0.05 level of significance, the data provides sufficient evidence to conclude that cell growth is equal to the nutrition. c. At the 0.05 level of significance, the data provides sufficient evidence to conclude that cell growth is dependent of nutrition. d. At the 0.05 level of significance, the data provides insufficient evidence to conclude that cell growth is dependent of nutrition.arrow_forwardA study was conducted to assess the impact of nutrient enrichment on zooplankton densities in A & B Islands. An ecologist sampled populations of zooplankton in these two locations and observed the nutrient enrichment level was higher in A island when compared with the level in B island. It is predicted the zooplankton densities in A island will be greater than those found in B island.arrow_forward
- An econometrician suspects that the residuals of her model might be autocorrelated. Explain the steps involved in testing this theory using the Durbin–Watson (DW) testarrow_forwardA survey of 28 employed workers found that the correlation coefficient between the number of years of post-secondary education and current annual income in dollars is -0.38. The researchers hypothesize a positive relationship between number of years of post-secondary education and annual income. What can the researchers conclude with α = 0.05? a) Obtain/compute the appropriate values to make a decision about H0. critical value= test statistic= b) effect size= C) 1)There is a significant positive relationship between years of post-secondary education and current annual income. 2)There is a significant negative relationship between years of post-secondary education and current annual income. 3) There is no significant relationship between years of post-secondary education and current annual income.arrow_forwardA fast-food chain decided to carry out an experiment to assess the influence of advertising expenditure on sales. Different relative changes in advertising expenditure, compared to the previous year, were made in eight regions of the country, and resulting changes in sales levels were observed the accompanying table shows the results. Increase in advertising expenditure (%) 0 5 15 20 25 30 35 40 Increase in sales (%) 5 10 18 25 35 50 60 65 Determine the value of ∑X, ∑X2, ∑Y, ∑Y2, ∑XY. Where X represent independent variable and Y for dependent variable. Determine and interpret the coefficient of correlation between the two variables. Determine the value of regressions coefficients and write down the simple linear regression model.…arrow_forward
- A fast-food chain decided to carry out an experiment to assess the influence of advertising expenditure on sales. Different relative changes in advertising expenditure, compared to the previous year, were made in eight regions of the country, and resulting changes in sales levels were observed the accompanying table shows the results. Increase in advertising expenditure (%) 0 5 15 20 25 30 35 40 Increase in sales (%) 5 10 18 25 35 50 60 65 Determine the value of ∑X, ∑X2, ∑Y, ∑Y2, ∑XY. Where X represent independent variable and Y for dependent variable. Determine and interpret the coefficient of correlation between the two variables. Determine the value of regressions coefficients and write down the simple linear regression model. Test the validity of the model…arrow_forwardIn a detailed study of the productivity of a laboratory, the age distribution of its workers was analyzed, and the results were as follows, the kurtosis coefficient is equal toarrow_forwardJ 2 RCT was conducted to evaluate efficacy and safety of drug simvastatin compared to placebo in reducing mortality and morbidity in patients with coronary heart disease. Subjects were followed up on average 5.4 years. Over the duration of the follow-up, 63 subjects died due to heart attack among 2,223 subjects in the placebo group compared to 30 deaths among 2,221 patients in the simvastatin drug group. 1. What is the Relative Risk or death from the heart attack in the simvastatin group?arrow_forward
- In recent years, concerns have been expressed about adverse health effects from amalgam dental restorations, which include mercury. The table below shows results from a study in which some patients were treated with amalgam restorations and others were treated with composite restorations that do not contain mercury (based on data from “Neuropsychological and Renal Effects of Dental Amalgam in Children,” by Bellinger, et al., Journal of the American Medical Association, Vol. 295, No. 15). Use a 0.05 significance level to test for independence between the type of restoration and sensory disorders. Do amalgam restorations appear to affect sensory disorders? Amalgam Composite Sensory disorder 36 28 No sensory disorder 231 239arrow_forwardA strain of genetically engineered cotton, known as Bt cotton, is resistant to certain insects, which results in larger yields of cotton. Farmers in northern China have increased the number of acres planted in Bt cotton. Because Bt cotton is resistant to certain pests, farmers have also reduced their use of insecticide. Scientists in China were interested in the long‑term effects of Bt cotton cultivation and decreased insecticide use on insect populations that are not affected by Bt cotton. One such insect is the mirid bug. Scientists measured the number of mirid bugs per 100 plants and the proportion of Bt cotton planted at 38 locations in northern China for the 12‑year period from 1997–2008. The scientists reported this regression analysis: number of mirid bugs per 100 plants=0.54+6.81× Bt cotton planting proportion ?2=0.90, ?<0.0001 What does the slope b=6.81 say about the relation between Bt cotton planting proportion and number of mirid bugs per 100 plants? - Scientists…arrow_forwardThe 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 correlation coefficient y between output and time under a load of 588 N was −0.9515. Measurements were taken 100 times per second for 300 seconds, for a total of 30,000 measurements. Find a 95% confidence interval for the population correlation ρ.arrow_forward
- MATLAB: An Introduction with ApplicationsStatisticsISBN:9781119256830Author:Amos GilatPublisher:John Wiley & Sons IncProbability and Statistics for Engineering and th...StatisticsISBN:9781305251809Author:Jay L. DevorePublisher:Cengage LearningStatistics for The Behavioral Sciences (MindTap C...StatisticsISBN:9781305504912Author:Frederick J Gravetter, Larry B. WallnauPublisher:Cengage Learning
- Elementary Statistics: Picturing the World (7th E...StatisticsISBN:9780134683416Author:Ron Larson, Betsy FarberPublisher:PEARSONThe Basic Practice of StatisticsStatisticsISBN:9781319042578Author:David S. Moore, William I. Notz, Michael A. FlignerPublisher:W. H. FreemanIntroduction to the Practice of StatisticsStatisticsISBN:9781319013387Author:David S. Moore, George P. McCabe, Bruce A. CraigPublisher:W. H. Freeman