2003 Cars. Data on 147 cars were obtained from ft the October 2002 issue of Road & Tra...

2003 Cars. Data on 147 cars were obtained from ft the October 2002 issue of Road & Track: The New Cars. The following data are available in a file named CARS8 on the CD:

name of car

weight, in pounds (WEIGHT)

mileage in city driving (CITYMPG)

mileage in highway driving (HWYMPG)

horsepower,@ 6300 rpm (HP)

number of cylinders (CYLIN)

displacement, in liters (LITER)

Using the available data, try to determine what factors involved in the construction of a car affect either mileage in city driving or mileage in highway driving. (Choose either CITYMPG or HWYMPG as your dependent variable. If you choose CITYMPG, do not use HWYMPG as a possible explanatory variable, and vice versa.) Use any of the techniques discussed to select appropriate variables. Be sure to examine scatterplots and residual plots for violations of assumptions and to correct for any such violations.

a. For the model you select, report the estimated regression. Be sure to define the variables used.

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b. For the model you select, report any corrections for violations of assumptions. Explain why the correction was needed and justify the correction you used.

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c. Justify your choice of variables from both a statistical and a practical standpoint.

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d. State any limitations of the model.

(Source: From Road & Track: The New Cars. Copyright 2002 by Hachette Filipacchi Magazines, Inc. Used with permission.)