8-2 [A] Analysis of Variance Sum of Mean Source DF Squares Square F Value Pr > F
Model 6 21.99716 3.66619 13.90 <.0001 Error 456 120.24145 0.26369 Corrected Total 462 142.23862
Root MSE 0.51351 R-Square 0.1546 Dependent Mean 3.99827 Adj R-Sq 0.1435 Coeff Var 12.84317
Parameter Estimates Parameter Standard Variance Variable Label DF Estimate Error t Value Pr > |t| Inflation
Intercept Intercept 1 4.06829 0.03673 beauty beauty 1 0.16561 0.03133 5.29 <.0001 1.02904 intro intro 1 0.01133 0.05575 0.20 0.8354 1.16786 onecredit onecredit 1 0.63453 0.10727 5.92 <.0001 1.19530 female female 1 -0.17348 0.04911 -3.53 0.0005 1.03950 minority minority 1 -0.16662 0.0669 -2.49 0.0294 1.21699 nnenglish nnenglish 1 -0.24416 0.09292 -2.63 0.0229 1.14131
[B] Analysis of Variance Sum of Mean Source DF Squares Square F Value Pr > F
1 Model 8 22.37105 2.79638 10.59 <.0001 Error 454 119.86757 0.26403 Corrected Total 462 142.23862 Root MSE 0.51383 R-Square 0.1573 Dependent Mean 3.99827 Adj R-Sq 0.1424 Coeff Var 12.85140
Parameter Estimates
Parameter Standard Variance Variable Label DF Estimate Error t Value Pr > |t| Inflation
Intercept Intercept 1 3.67703 0.5444 6.75 <.0001 0 beauty beauty 1 0.15965 0.03034 5.26 <.0001 1.11228 intro intro 1 0.00244 0.05589 0.04 0.9646 1.18976 onecredit onecredit 1 0.61976 0.10753 5.76 <.0001 1.21492 female female 1 -0.18812 0.0512 -3.67 0.0003 1.12685 minority minority 1 -0.17957 0.06861 -2.62 0.0204 1.24450 nnenglish nnenglish 1 -0.24322 0.09504 -2.56 0.0235 1.14137 age age 1 0.01953 0.02324 0.84 0.3977 89.46953 age2 age2 1 -0.00022230 0.00024183 -0.92 0.3490 90.42791
[C] Sum of Mean Source DF Squares Square F Value Pr > F
Model 7 23.31468 3.33067 12.74 <.0001 Error 455 118.92393 0.26137 Corrected Total 462 142.23862 Root MSE 0.51124 R-Square 0.1639 Dependent Mean 3.99827 Adj R-Sq 0.1510 Coeff Var 12.78664
2 Parameter Estimates Parameter Standard Variance Variable Label DF Estimate Error t Value Pr > |t| Inflation
Intercept Intercept 1 4.07495 0.03702 108.68 <.0001 0 beauty beauty 1 0.23082 0.04219 5.47 <.0001 1.95646 intro intro 1 -0.00123 0.05453 -0.02 0.9820 1.18027 onecredit onecredit 1 0.65658 0.11128 5.90 <.0001 1.20468 female female 1 -0.17295 0.04906 -3.52 0.0005 1.03952 minority minority 1 -0.13474 0.07726 -1.74 0.0818 1.25951 nnenglish nnenglish 1 -0.26791 0.10701 -2.50 0.0126 1.15256 FemBeau FemBeau 1 -0.14074 0.06269 -2.25 0.0252 1.97358
Estimate SE t Intercept Intercept 4.07495 0.00137 0.037016 110.087 beauty beauty 0.23082 0.002244 0.047367 4.872999 intro intro -0.00123 0.003033 0.05507 -0.02234 onecredit onecredit 0.65658 0.01158 0.10761 6.101504 female female -0.17295 0.002395 0.048939 -3.53398 minority minority -0.13474 0.004711 0.068633 -1.96318 nnenglish nnenglish -0.26791 0.008478 0.092074 -2.90974 FemBeau FemBeau -0.14074 0.003945 0.062809 -2.24076
[D] Analysis Variable : beauty beauty
Mean Std Dev Maximum Minimum ƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒ 6.2634989E-8 0.7886477 1.9700230 -1.4504940 ƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒƒ
Before -0.7886477 After +0.7886477
3 Recall that the standard deviation of Beauty is 0.79. Thus Professor Smith’s course rating is expected to increase by 0.231 (2 0.79) 0.37. The 95% confidence interval for the increase is (0.231 1.96 0.048) (2 0.79) or 0.22 to 0.51.
8-3 [A] Sum of Mean Source DF Squares Square F Value Pr > F Model 12 3541.59432 295.13286 124.81 <.0001 Error 3783 8945.78819 2.36473 Corrected Total 3795 12487
Root MSE 1.53777 R-Square 0.2836 Dependent Mean 13.82929 Adj R-Sq 0.2813 Coeff Var 11.11965
Parameter Estimates Parameter Standard Variance Variable Label DF Estimate Error t Value Pr > |t| Inflation
4 Intercept Intercept 1 8.92082 0.25159 35.46 <.0001 0 dist dist 1 -0.03666 0.01272 -2.88 0.0040 1.18144 female female 1 0.14297 0.05044 2.83 0.0046 1.01250 bytest bytest 1 0.09304 0.00318 29.24 <.0001 1.26355 tuition tuition 1 -0.19105 0.10088 -1.89 0.0583 1.31336 black black 1 0.35061 0.07123 4.92 <.0001 1.26639 hispanic hispanic 1 0.36176 0.07727 4.68 <.0001 1.22131 incomehi incomehi 1 0.37183 0.06072 6.12 <.0001 1.20952 ownhome ownhome 1 0.13855 0.06672 2.08 0.0379 1.05811 dadcoll dadcoll 1 0.57097 0.07370 7.75 <.0001 1.40561 momcoll momcoll 1 0.37781 0.08153 4.63 <.0001 1.27962 cue80 cue80 1 0.02868 0.00987 2.91 0.0037 1.28283 stwmfg80 stwmfg80 1 -0.04250 0.02021 -2.10 0.0355 1.22004
estimate se t Intercept 8.92082 0.059069 0.243041 36.70496 dist -0.03666 0.000145 0.012054 -3.04127 female 0.14297 0.002519 0.050186 2.848825 bytest 0.09304 9.05E-06 0.003009 30.92207 tuition -0.19105 0.009674 0.098357 -1.94241 black 0.35061 0.004531 0.067315 5.20853 hispanic 0.36176 0.00582 0.076287 4.742065 incomehi 0.37183 0.003858 0.062111 5.986538 ownhome 0.13855 0.004208 0.064868 2.13587 dadcoll 0.57097 0.005802 0.076172 7.495797 momcoll 0.37781 0.006948 0.083357 4.532444 cue80 0.02868 9.04E-05 0.009507 3.016874 stwmfg80 -0.0425 0.000396 0.019901 -2.13553
5 [C] Sum of Mean Source DF Squares Square F Value Pr > F Model 13 3551.12555 273.16350 115.61 <.0001 Error 3782 8936.25695 2.36284 Corrected Total 3795 12487
Root MSE 1.53715 R-Square 0.2844 Dependent Mean 13.82929 Adj R-Sq 0.2819 Coeff Var 11.11519
Parameter Estimates Parameter Standard Variance Variable Label DF Estimate Error t Value Pr > |t| Inflation
Intercept Intercept 1 9.01217 0.25556 35.26 <.0001 0 dist dist 1 -0.08117 0.02555 -3.18 0.0015 4.77345 dist2 dist2 1 0.00464 0.00231 2.01 0.0447 4.70910 female female 1 0.14331 0.05042 2.84 0.0045 1.01251 bytest bytest 1 0.09264 0.00319 29.07 <.0001 1.26853 tuition tuition 1 -0.19282 0.10084 -1.91 0.0559 1.31346 black black 1 0.33393 0.07168 4.66 <.0001 1.28362 hispanic hispanic 1 0.33331 0.07853 4.24 <.0001 1.26240 incomehi incomehi 1 0.36950 0.06071 6.09 <.0001 1.20997 ownhome ownhome 1 0.14327 0.06674 2.15 0.0319 1.05943 dadcoll dadcoll 1 0.56116 0.07383 7.60 <.0001 1.41179
6 momcoll momcoll 1 0.37770 0.08149 4.63 <.0001 1.27962 cue80 cue80 1 0.02595 0.00995 2.61 0.0092 1.30706 stwmfg80 stwmfg80 1 -0.04255 0.02020 -2.11 0.0352 1.22005
estimate se t Intercept 9.01217 0.062209 0.249418 36.13278 dist -0.08117 0.000628 0.025065 -3.23839 dist2 0.00464 4.20E-06 0.00205 2.262976 female 0.14331 0.002516 0.050158 2.857151 bytest 0.09264 9.11E-06 0.003019 30.68841 tuition -0.19282 0.009677 0.09837 -1.96014 black 0.33393 0.004648 0.068178 4.897882 hispanic 0.33331 0.006043 0.077735 4.287763 incomehi 0.3695 0.003867 0.062185 5.941918 ownhome 0.14327 0.004194 0.064762 2.212257 dadcoll 0.56116 0.005843 0.076439 7.341293 momcoll 0.3777 0.006947 0.083348 4.53158 cue80 0.02595 9.16E-05 0.009569 2.711788 stwmfg80 -0.04255 0.000396 0.01989 -2.13927
7 (c) When Dist increases from 2 to 3, the predicted change in ED is: (0.081*30.0046*3^2)-(0.081*20.0046*2^2) 0.058. This means that the number of years of completed education is predicted to decrease by 0.058 years. When Dist increases from 6 to 7, the predicted change in ED is: (0.081*70.0046*7^2)-(0.081*60.0046*6^2) 0.021. This means that the number of years of completed education is predicted to decrease by 0.021 years. (d) The regression in (3) adds the variable Dist2 to regression (1). The coefficient on Dist2 is statistically significant ( t 2.26) and this suggests that the addition of Dist2 is important. Thus, (4) is preferred to (1).
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