The article “The Influence of Corrosion Inhibitor and Surface Abrasion on the Failure of Aluminum-Wired Twist-On Connections” (IEEE Trans. on Components, Hybrids, and Manuf. Tech., 1984: 20–25) reported data on potential drop measurements for one sample of connectors wired with alloy aluminum and another sample wired with EC aluminum. Does the accompanying SAS output suggest that the true average potential drop for alloy connections (type 1) is higher than that wfor EC connections (as stated in the article)? Carry out the appropriate test using a significance level of .01. In reaching your conclusion, what type of error might you have committed? [Note: SAS reports the P-value for a two-tailed test.]
Type | N | Mean | Std Dev | Std Error |
1 | 20 17.49900000 | 0.55012821 | 0.12301241 | |
2 | 20 16.90000000 | 0.48998389 | 0.10956373 | |
Variances | T DF | Prob>|T| | ||
Unequal | 3.6362 37.5 | 0.0008 | ||
Equal | 3.6362 38.0 | 0.0008 |
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Chapter 9 Solutions
Probability and Statistics for Engineering and the Sciences
- The decline of salmon fisheries along the Columbia River in Oregon has caused great concern among commercial and recreational fishermen. The paper 'Feeding of Predaceous Fishes on Out-Migrating Juvenile Salmonids in John Day Reservoir, Columbia River' (Trans. Amer. Fisheries Soc. (1991: 405-420) gave the accompanying data on y = maximum size of salmonids consumed by a northern squaw fish (the most abundant salmonid predator) and x = squawfish length, both in mm. Here is the computer software printout of the summary: Coefficients: Estimate Std. Error t value Pr(> |t|) (Intercept) −89.010 16.720 −5.324 0.000 Length 0.704 0.049 14.333 0.000 Using this information, give the equation of the least squares regression line.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_forwardThe article "Change in Creep Behavior of Plexiform Bone with Phosphate Ion Treatment" (R. Regimbal, C. DePaula, and N. Guzelsu, Bio-Medical Materials and Engineering, 2003:11-25) describes an experiment to study the effects of saline and phosphate ion solutions on mechanical properties of plexiform bone. The following table presents the yield stress measurements for six specimens treated with either saline (NaCI) or phosphate ion (Na,HPO4) solution, at a temperature of either 25°C or 37°C. (The article presents means and standard deviations only; the values in the table are consistent with these.) Solution Temperature NaCl Yield Stress (MPa) 138.40 130.89 94.646 96.653 116.90 88.215 25°C NaCl 37°C 92.312 147.28 116.48 88.802 114.37 90.737 Na,HPO, 25°C 120.18 129.43 139.76 132.75 137.23 121.73 Na,HPO4 37°C 123.50 128.94 102.86 99.941 161.68 136.44 a. Estimate all main effects and interactions. b. Construct an ANOVA table. You may give ranges for the P-values. Is the additive model…arrow_forward
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- The article “Effect of Varying Solids Concentration and Organic Loading on the Performance of Temperature Phased Anaerobic Digestion Process” (S. Vandenburgh and T. Ellis, Water Environment Research, 2002:142–148) discusses experiments to determine the effect of the solids concentration on the performance of treatment methods for wastewater sludge. In the first experiment, the concentration of solids (in g/L) was 43.94 ± 1.18. In the second experiment, which was independent of the first, the concentration was 48.66 ± 1.76. Estimate the difference in the concentration between the two experiments, and find the uncertainty in the estimate.arrow_forwardsto ave 12.72 (M4) The authors of the paper "Serum Zinc Levels of Cord Blood: Relation to Birth Weight and Gestational Period" (Journal of Trace Elements in Medicine and Biology [2015]: 180-183) car- ried out a study of zinc levels of low-birth-weight babies and normal-birth-weight babies. For a sample of 50 low- birth-weight babies, the sample mean zinc level was 17.00 and the standard error was 0.43. For a sample of 73 normal-birth-weight babies, the sample mean zinc level was 18.16 and the standard error was 0.32. Explain why the two standard errors are not the same.arrow_forwardThe article "Influence of Freezing Temperature on Hydraulic Conductivity of Silty Clay" (J. Konrad and M. Samson, Journal of Geotechnical and Geoenvironmental Engineering, 2000:180–187) describes a study of factors affecting hydraulic conductivity of soils. The measurements of hydraulic conductivity in units of 108 cm/s (y), initial void ratio (x), and thawed void ratio (x2) for 12 specimens of silty clay are presented in the following table. y 1.01 1.12 1.04 1.30 1.01 1.04 0.955 1.15 1.23 1.28 1.23 1.30 0.84 0.88 0.85 0.95 0.88 0.86 0.85 0.89 0.90 0.94 0.88 0.90 X1 0.81 0.85 0.87 0.92 0.84 0.85 0.85 0.86 0.85 0.92 0.88 0.92 X2 Fit the model y = Bo + fix1 + e. For each coefficient, test the null hypothesis that it is equal to 0. Fit the model y = Bo + Bzx2 + e. For each coefficient, test the null hypothesis that it is equal to 0. Fit the model y = Bo + BzX1 + Bzxz + e. For each coefficient, test the null hypothesis that it is equal to 0. d. Which of the models in parts (a) to (c) is…arrow_forward
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