Data was collected on 54 observations on a response of interest, y, and four potential predictor variables x1, x2, x3, and x4. The output from regression analyses of the data is attached to the end of the page. d) Is the variable from your best simple linear regression model (from part a) included in the model with the lowest overall MSE (part b)? Briefly explain why it could happen that the best single variable is not in the best overall model. e) Following the best subsets regression results, the sums of squares for regression and error (also called residual) are displayed for several models. Using the regression sums of squares information for the full model containing all four x variables, calculate i) the R2 value for the full model, ii) the F statistic for the test of the H0: b1 = b2 = b3 = b4 = 0, and iii) the standard deviation of the residuals for the full model. f) Using the regression sums of squares information, test the null hypothesis H0:b2 = b4 = 0 for the full model. (Calculate an F statistic, obtain a tabled F value, and report the conclusion of your test, use a = .05). g)  Using the regression sums of squares information, for the model containing the terms x1, x2 and x4, calculate the t statistic for the hypothesis H0: b1 = 0, where b1 is the coefficient of x1. (Hint: first calculate an F statistic for H0 and then take its square root to obtain the t value. Assume all regression coefficients are positive.)

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter4: Equations Of Linear Functions
Section4.6: Regression And Median-fit Lines
Problem 4GP
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  1. Data was collected on 54 observations on a response of interest, y, and four potential predictor variables x1, x2, x3, and x4. The output from regression analyses of the data is attached to the end of the page.

d) Is the variable from your best simple linear regression model (from part a) included in the model with the lowest overall MSE (part b)? Briefly explain why it could happen that the best single variable is not in the best overall model.

e) Following the best subsets regression results, the sums of squares for regression and error (also called residual) are displayed for several models. Using the regression sums of squares information for the full model containing all four x variables, calculate i) the R2 value for the full model, ii) the F statistic for the test of the H0: b1 = b2 = b3 = b4 = 0, and iii) the standard deviation of the residuals for the full model.

f) Using the regression sums of squares information, test the null hypothesis H0:b2 = b4 = 0 for the full model. (Calculate an F statistic, obtain a tabled F value, and report the conclusion of your test, use a = .05).

g)  Using the regression sums of squares information, for the model containing the terms x1, x2 and x4, calculate the t statistic for the hypothesis H0: b1 = 0, where b1 is the coefficient of x1. (Hint: first calculate an F statistic for H0 and then take its square root to obtain the t value. Assume all regression coefficients are positive.)

The REG Procedure
4
Results for the best subsets regression analysis
R-Square Selection Method
Root
Number in
Model R-Square C(p) MSE
1 0.5259 757.7545 0.19035
1 0.4414 901.7010 0.20662
1 0.3447 1066.354 0.22378
0.1257 1439.527 0.25849
1
Dependent Variable: y
3
0.9712
0.8758 165.5890 0.09935
3
3
0.7215 428.5088 0.14878
3 0.6449 558.9234 0.16799
2 0.8049 284.3219 0.12329
-227.5857
-202.2469
2
0.6847 489.1148 0.15673
x2 x3
x3 x4
x1 x3
2 0.6521 544.6919 0.16464 -197.0205
0.6440 558.4141 0.16654 -195.8044 x2 x4
2
BIC Variables in Model
-180.6717 x4
-171.8944 x3
x2
x3
x1, x3
x2, x4
-163.3427 x2
-147.8645 x1
3.0002 0.04781 -321.7335 x1 x2 x3
-250.6043 x2 x3 x4
-208.5846 x1 x3 x4
-195.7567 x1 x2 x4
x1, x2, x3
x1, x2, x4
x1, x2, x3, x4
0.9712 5.0000 0.04830 -319.5296 x1 x2 x3 x4
Results from several models to predict y using various combinations of x variables
Terms in model
SSRegression
SSE or SSResidual
1.36979
1.75385
2.59127
2.55926
3.85947
2.56274
3.85947
2.60397
2.21991
1.38250
1.41450
0.11430
1.41103
0.11430
Transcribed Image Text:The REG Procedure 4 Results for the best subsets regression analysis R-Square Selection Method Root Number in Model R-Square C(p) MSE 1 0.5259 757.7545 0.19035 1 0.4414 901.7010 0.20662 1 0.3447 1066.354 0.22378 0.1257 1439.527 0.25849 1 Dependent Variable: y 3 0.9712 0.8758 165.5890 0.09935 3 3 0.7215 428.5088 0.14878 3 0.6449 558.9234 0.16799 2 0.8049 284.3219 0.12329 -227.5857 -202.2469 2 0.6847 489.1148 0.15673 x2 x3 x3 x4 x1 x3 2 0.6521 544.6919 0.16464 -197.0205 0.6440 558.4141 0.16654 -195.8044 x2 x4 2 BIC Variables in Model -180.6717 x4 -171.8944 x3 x2 x3 x1, x3 x2, x4 -163.3427 x2 -147.8645 x1 3.0002 0.04781 -321.7335 x1 x2 x3 -250.6043 x2 x3 x4 -208.5846 x1 x3 x4 -195.7567 x1 x2 x4 x1, x2, x3 x1, x2, x4 x1, x2, x3, x4 0.9712 5.0000 0.04830 -319.5296 x1 x2 x3 x4 Results from several models to predict y using various combinations of x variables Terms in model SSRegression SSE or SSResidual 1.36979 1.75385 2.59127 2.55926 3.85947 2.56274 3.85947 2.60397 2.21991 1.38250 1.41450 0.11430 1.41103 0.11430
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