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ProblemSet_3_08B

# ProblemSet_3_08B - ESM 206 Problem Set 3 Micro-Exam will be...

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ESM 206 Problem Set 3 Micro-Exam will be due Tuesday, Feb. 5 at 4 PM. A. For this section use the Cars_1993.xls data on the course website. 1) Use regression to answer the following question: “All else being equal, how would a 100 pound reduction in a car’s weight affect its highway fuel mileage?” 2) Write down the equation corresponding to the analysis you just did, and identify the variables, the parameters, and the residuals. What was your estimate of each parameter and of the residual variance? What was the 95% confidence interval for each of your parameter estimates? 3) I ran a model in which the dependent variable was highway mileage and the independent variables were weight and the interaction between weight and engine size, and got the output shown below (it is from JMP, but you should be able to find the key elements of the output). Explain in words the meaning of the interaction term and what the results suggest about how engine size affects fuel economy. Response HighwayMPG Whole Model Summary of Fit RSquare 0.676073 RSquare Adj 0.668794 Root Mean Square Error 3.075279 Mean of Response 29.13043 Observations (or Sum Wgts) 92 Analysis of Variance Source DF Sum of Squares Mean Square F Ratio Model 2 1756.7316 878.366 92.8766 Error 89 841.7031 9.457 Prob > F C. Total 91 2598.4348 <.0001 Lack Of Fit Source DF Sum of Squares Mean Square F Ratio Lack Of Fit 82 808.70315 9.86223 2.0920 Pure Error 7 33.00000 4.71429 Prob > F Total Error 89 841.70315 0.1521 Max RSq 0.9873 Parameter Estimates Term Estimate Std Error t Ratio Prob>|t| Intercept 56.472278 2.660277 21.23 <.0001 Weight -0.009941 0.001224 -8.12 <.0001 EngineSize*Weight 0.0003637 0.000152 2.40 0.0187 Effect Tests Source Nparm DF Sum of Squares

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ProblemSet_3_08B - ESM 206 Problem Set 3 Micro-Exam will be...

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