The "car data" (on sakai) are observations of cars sold in the North American market. Five variables were collected for each car: Weight, Disp. (the engine displacement in liters), Mileage, Fuel, and Type.

1) Fit the following regression model: Mileage = a + b1 * weight + b2 * Disp + b3*Fuel + b4*Type+ error [Hint: Use PROC GLM rather than PROC REG and use the class statement in GLM. Report the coefficient estimates and check the estimated coefficients by adding the "selection" option to the MODEL statement.]

2) new data set which does not contain the "Type" variable. Find the best regression model for this new data set. [Hint: Now we can use PROC REG.] If you are interested, you can add the option 'SELECTION': MODEL Mileage = Weight Disp Fuel/SELECTION = backward; /*forward, stepwise*/

3) Preform model checking procedures for the regression model you created in Part 2. For parts 1-3 make sure you have clear titles for the output and labels for the variables.

car Weight Disp. Mileage Fuel Type Eagle Summit 4 2560 97 33 3.030303 Small Ford Escort 4 2345 114 33 3.030303 Small Ford Festiva 4 1845 81 37 2.702703 Small Honda Civic 4 2260 91 32 3.125000 Small Mazda Protege 4 2440 113 32 3.125000 Small Mercury Tracer 4 2285 97 26 3.846154 Small Nissan Sentra 4 2275 97 33 3.030303 Small Pontiac LeMans 4 2350 98 28 3.571429 Small Subaru Loyale 4 2295 109 25 4.000000 Small Subaru Justy 3 1900 73 34 2.941176 Small Toyota Corolla 4 2390 97 29 3.448276 Small Toyota Tercel 4 2075 89 35 2.857143 Small Volkswagen Jetta 4 2330 109 26 3.846154 Small Chevrolet Camaro V8 3320 305 20 5.000000 Sporty Dodge Daytona 2885 153 27 3.703704 Sporty Ford Mustang V8 3310 302 19 5.263158 Sporty Ford Probe 2695 133 30 3.333333 Sporty Honda Civic CRX Si 4 2170 97 33 3.030303 Sporty Honda Prelude Si 4WS 4 2710 125 27 3.703704 Sporty Nissan 240SX 4 2775 146 24 4.166667 Sporty Plymouth Laser 2840 107 26 3.846154 Sporty Subaru XT 4 2485 109 28 3.571429 Sporty Audi 80 4 2670 121 27 3.703704 Compact Buick Skylark 4 2640 151 23 4.347826 Compact Chevrolet Beretta 4 2655 133 26 3.846154 Compact Chrysler Le Baron V6 3065 181 25 4.000000 Compact Ford Tempo 4 2750 141 24 4.166667 Compact Honda Accord 4 2920 132 26 3.846154 Compact Mazda 626 4 2780 133 24 4.166667 Compact Mitsubishi Galant 4 2745 122 25 4.000000 Compact Mitsubishi Sigma V6 3110 181 21 4.761905 Compact Nissan Stanza 4 2920 146 21 4.761905 Compact Oldsmobile Calais 4 2645 151 23 4.347826 Compact Peugeot 405 4 2575 116 24 4.166667 Compact Subaru Legacy 4 2935 135 23 4.347826 Compact Toyota Camry 4 2920 122 27 3.703704 Compact Volvo 240 4 2985 141 23 4.347826 Compact Acura Legend V6 3265 163 20 5.000000 Medium Buick Century 4 2880 151 21 4.761905 Medium Chrysler Le Baron Coupe 2975 153 22 4.545455 Medium Chrysler New Yorker V6 3450 202 22 4.545455 Medium Eagle Premier V6 3145 180 22 4.545455 Medium Ford Taurus V6 3190 182 22 4.545455 Medium Ford Thunderbird V6 3610 232 23 4.347826 Medium Hyundai Sonata 4 2885 143 23 4.347826 Medium Mazda 929 V6 3480 180 21 4.761905 Medium Nissan Maxima V6 3200 180 22 4.545455 Medium Oldsmobile Cutlass Ciera 4 2765 151 21 4.761905 Medium Oldsmobile Cutlass Supreme V6 3220 189 21 4.761905 Medium Toyota Cressida 6 3480 180 23 4.347826 Medium Buick Le Sabre V6 3325 231 23 4.347826 Large Chevrolet Caprice V8 3855 305 18 5.555556 Large Ford LTD Crown Victoria V8 3850 302 20 5.000000 Large Chevrolet Lumina APV V6 3195 151 18 5.555556 Van Dodge Grand Caravan V6 3735 202 18 5.555556 Van Ford Aerostar V6 3665 182 18 5.555556 Van Mazda MPV V6 3735 181 19 5.263158 Van Mitsubishi Wagon 4 3415 143 20 5.000000 Van Nissan Axxess 4 3185 146 20 5.000000 Van Nissan Van 4 3690 146 19 5.263158 Van