In: Statistics and Probability
The accompanying data resulted from a study of the relationship between y = brightness of finished paper and the independent variables
x1 = hydrogen peroxide (% by weight), x2 = sodium hydroxide (% by weight), x3 = silicate (% by weight), and x4 = process temperature.
x1 | x2 | x3 | x4 | y |
---|---|---|---|---|
0.2 | 0.2 | 1.5 | 145 | 83.9 |
0.4 | 0.2 | 1.5 | 145 | 84.9 |
0.2 | 0.4 | 1.5 | 145 | 83.4 |
0.4 | 0.4 | 1.5 | 145 | 84.2 |
0.2 | 0.2 | 3.5 | 145 | 83.8 |
0.4 | 0.2 | 3.5 | 145 | 84.7 |
0.2 | 0.4 | 3.5 | 145 | 84.0 |
0.4 | 0.4 | 3.5 | 145 | 84.8 |
0.2 | 0.2 | 1.5 | 175 | 84.5 |
0.4 | 0.2 | 1.5 | 175 | 86.0 |
0.2 | 0.4 | 1.5 | 175 | 82.6 |
0.4 | 0.4 | 1.5 | 175 | 85.1 |
0.2 | 0.2 | 3.5 | 175 | 84.5 |
0.4 | 0.2 | 3.5 | 175 | 86.0 |
0.2 | 0.4 | 3.5 | 175 | 84.0 |
0.4 | 0.4 | 3.5 | 175 | 85.4 |
x1 | x2 | x3 | x4 | y |
---|---|---|---|---|
0.1 | 0.3 | 2.5 | 160 | 82.9 |
0.5 | 0.3 | 2.5 | 160 | 85.5 |
0.3 | 0.1 | 2.5 | 160 | 85.2 |
0.3 | 0.5 | 2.5 | 160 | 84.5 |
0.3 | 0.3 | 0.5 | 160 | 84.7 |
0.3 | 0.3 | 4.5 | 160 | 85.0 |
0.3 | 0.3 | 2.5 | 130 | 84.9 |
0.3 | 0.3 | 2.5 | 190 | 84.0 |
0.3 | 0.3 | 2.5 | 160 | 84.5 |
0.3 | 0.3 | 2.5 | 160 | 84.7 |
0.3 | 0.3 | 2.5 | 160 | 84.6 |
0.3 | 0.3 | 2.5 | 160 | 84.9 |
0.3 | 0.3 | 2.5 | 160 | 84.9 |
0.3 | 0.3 | 2.5 | 160 | 84.5 |
0.3 | 0.3 | 2.5 | 160 | 84.6 |
(a) Find the estimated regression equation for the model that includes all independent variables, all quadratic terms, and all interaction terms. (Round your answers to four decimal places.)
= ____ + _____ x1 + ____ x2 + ____ x3 + ____ x4 + _____ x12 + _____ x22 + ______ x32 + _____ x42 + ______ x1x2 + _____ x1x3 + _____ x1x4 + _____ x2x3 + ______ x2x4 + ______ x3x4
(b) Calculate SSResid. (Round your answer to four decimal places.)
SSResid =
using excel>data>data analysis>Regression
we have
SUMMARY OUTPUT | ||||||||
Regression Statistics | ||||||||
Multiple R | 0.940495 | |||||||
R Square | 0.884531 | |||||||
Adjusted R Square | 0.783496 | |||||||
Standard Error | 0.3529 | |||||||
Observations | 31 | |||||||
ANOVA | ||||||||
df | SS | MS | F | Significance F | ||||
Regression | 14 | 15.26416 | 1.090297 | 8.754683 | 4.97E-05 | |||
Residual | 16 | 1.992619 | 0.124539 | |||||
Total | 30 | 17.25677 | ||||||
Coefficients | Standard Error | t Stat | P-value | Lower 95% | Upper 95% | Lower 95.0% | Upper 95.0% | |
Intercept | 76.43709 | 9.081796 | 8.416517 | 2.85E-07 | 57.18454 | 95.68963 | 57.18454 | 95.68963 |
x1 | -7.34524 | 10.79946 | -0.68015 | 0.506133 | -30.2391 | 15.5486 | -30.2391 | 15.5486 |
x2 | 9.613095 | 10.79946 | 0.890146 | 0.386577 | -13.2807 | 32.50693 | -13.2807 | 32.50693 |
x3 | -0.91488 | 1.067606 | -0.85695 | 0.404128 | -3.1781 | 1.348342 | -3.1781 | 1.348342 |
x4 | 0.096323 | 0.098342 | 0.979465 | 0.341929 | -0.11215 | 0.304799 | -0.11215 | 0.304799 |
X12 | -13.4524 | 6.599354 | -2.03844 | 0.058386 | -27.4424 | 0.537625 | -27.4424 | 0.537625 |
X22 | 2.797619 | 6.599354 | 0.423923 | 0.677266 | -11.1924 | 16.78763 | -11.1924 | 16.78763 |
X32 | 0.027976 | 0.065994 | 0.423923 | 0.677266 | -0.11192 | 0.167876 | -0.11192 | 0.167876 |
X42 | -0.00032 | 0.000293 | -1.09138 | 0.29127 | -0.00094 | 0.000302 | -0.00094 | 0.000302 |
X1X2 | 3.75 | 8.82251 | 0.425049 | 0.676462 | -14.9529 | 22.45289 | -14.9529 | 22.45289 |
X1X3 | -0.75 | 0.882251 | -0.8501 | 0.407812 | -2.62029 | 1.120289 | -2.62029 | 1.120289 |
X1X4 | 0.141667 | 0.058817 | 2.408612 | 0.028428 | 0.016981 | 0.266353 | 0.016981 | 0.266353 |
X2X3 | 2 | 0.882251 | 2.266929 | 0.037608 | 0.129711 | 3.870289 | 0.129711 | 3.870289 |
X2X4 | -0.125 | 0.058817 | -2.12525 | 0.049491 | -0.24969 | -0.00031 | -0.24969 | -0.00031 |
X3X4 | 0.003333 | 0.005882 | 0.566732 | 0.57876 | -0.00914 | 0.015802 | -0.00914 | 0.015802 |
a) the estimated regression equation for the model that includes all independent variables, all quadratic terms, and all interaction terms is
= 76.4371 -7.3452 x1 + 9.6131 x2 -0.9149 x3 +0.0963 x4 -13.4524 x12 +2.7976 x22 +0.0280 x32 -0.0003 x42 + 3.7500 x1x2 -0.7500 x1x3 + 0.1416 x1x4 + 2.000 x2x3 -0.1250 x2x4 +0.0033 x3x4
(b)
SSResid = 1.9926