Investigation 9

Investigation 9 - (8607, 17783) Values of Predictors for...

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Vanessa Reapor Statistics 252, Section 07 February 16, 2010 Investigation 9: Used Car Prices A) Graph Attached. B) Proportion of Variability in Car Prices: R 2 = 67.3% or .673 C) H 0 : β 1 = 0 H A : β 1 < 0 Test Statistic: T = -13.45 P-Value: .000, Reject H 0 Conclusion: Overwhelming evidence of a negative linear relationship between price and age in the population of Honda Civics for sales online. Regression Analysis: Price versus age The regression equation is Price = 18785 - 1397 age Predictor Coef SE Coef T P Constant 18785.3 431.0 43.59 0.000 age -1397.5 103.9 -13.45 0.000 S = 2295.21 R-Sq = 67.3% R-Sq(adj) = 66.9% D) 95% Confidence Interval for Population Slope Coefficient: Interpretation: We are 95% confident that the predicted decrease in price for each additional decrease in manufacture year is between (-1604.9688) and (-1190.0312).
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E) 95% Confidence Interval for the Average Price of a 4-Year-Old Car: (12701, 13690) Predicted Values for New Observations New Obs Fit SE Fit 95% CI 95% PI 1 13195 249 (12701, 13690)
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Unformatted text preview: (8607, 17783) Values of Predictors for New Observations New Obs age 1 4.00 F) 95% Prediction Interval for the Price of a 4-Year-Old Car: (8607, 17783) Predicted Values for New Observations New Obs Fit SE Fit 95% CI 95% PI 1 13195 249 (12701, 13690) (8607, 17783) Values of Predictors for New Observations New Obs age 1 4.00 95% Prediction Interval for the Price of a 10-Year-Old Car: (28, 9593) Predicted Values for New Observations New Obs Fit SE Fit 95% CI 95% PI 1 4811 724 (3372, 6249) (28, 9593)X X denotes a point that is an outlier in the predictors. Values of Predictors for New Observations New Obs age 1 10.0 G) These prediction intervals are similar to each other because both are wider compared to the confidence intervals. For instance the width of the 4 Year Old Car is 9176, and the width of the 10 Year Old Car is 9565. Also, the predicted intervals share the same midpoints with their respected confidence interval of the specific year....
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Investigation 9 - (8607, 17783) Values of Predictors for...

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