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(15 marks) One study examined the impact of temperature on the viscosity of iven

ID: 3065969 • Letter: #

Question

(15 marks) One study examined the impact of temperature on the viscosity of iven in the following table, where temper toluene-tetralin blends. The data are g ature is measured in °C and viscosity is in mPa-s. Temperature 24.935.044.955.165.275.285.295.2 Viscosity 1.133 0.977 0.853 0.755 0.672 0.602 0.542 0.507 (a) (6 marks) Plot the data and fit the simple linear regression model. Is the linear model a good fit for the data? (Include residual analysis here.) (b) (7 marks) Fit a quadratic model. Present the residual analysis and the fitted model. Also include the scatter plot with fitted quadratic line (c) (2 marks) What proportion of the variation in viscosity can be explained by the quadratic model in (b)?

Explanation / Answer

a)

SUMMARY OUTPUT

Regression Statistics

Multiple R

0.980

R Square

0.960

Adjusted R Square

0.954

Standard Error

0.047

Observations

8

ANOVA

df

SS

MS

F

Significance F

Regression

1

0.325

0.325

144.727

0.000

Residual

6

0.013

0.002

Total

7

0.339

Coefficients

Standard Error

t Stat

P-value

Lower 95%

Upper 95%

Intercept

1.281

0.047

27.350

0.000

1.167

1.396

Temperature

-0.009

0.001

-12.030

0.000

-0.011

-0.007

RESIDUAL OUTPUT

PROBABILITY OUTPUT

Observation

Predicted Viscosity

Residuals

Standard Residuals

Percentile

Viscosity

1

1.063365838

0.069634162

1.586089461

6.25

0.507

2

0.974890315

0.002109685

0.048053272

18.75

0.542

3

0.888166783

-0.035166783

-0.801010041

31.25

0.602

4

0.798815264

-0.043815264

-0.998000505

43.75

0.672

5

0.710339742

-0.038339742

-0.873281993

56.25

0.755

6

0.622740214

-0.020740214

-0.472409427

68.75

0.853

7

0.535140686

0.006859314

0.156237755

81.25

0.977

8

0.447541159

0.059458841

1.354321478

93.75

1.133

b)

SUMMARY OUTPUT

Regression Statistics

Multiple R

0.9996

R Square

0.9992

Adjusted R Square

0.9989

Standard Error

0.0071

Observations

8

ANOVA

df

SS

MS

F

Significance F

Regression

2

0.339

0.169

3319.530

0.000

Residual

5

0.000

0.000

Total

7

0.339

Coefficients

Standard Error

t Stat

P-value

Lower 95%

Upper 95%

Intercept

1.553

0.018

85.082

0.000

1.506

1.599

Temperature

-0.019

0.001

-29.040

0.000

-0.021

-0.018

Temperature^2

0.000

0.000

16.108

0.000

0.000

0.000

RESIDUAL OUTPUT

PROBABILITY OUTPUT

Observation

Predicted Viscosity

Residuals

Standard Residuals

Percentile

Viscosity

1

1.125549253

0.007450747

1.23429054

6.25

0.507

2

0.983492198

-0.006492198

-1.075497339

18.75

0.542

3

0.861693737

-0.008693737

-1.440204122

31.25

0.602

4

0.75426852

0.00073148

0.121176988

43.75

0.672

5

0.665961479

0.006038521

1.000341101

56.25

0.755

6

0.596238675

0.005761325

0.954420854

68.75

0.853

7

0.544137671

-0.002137671

-0.354126512

81.25

0.977

8

0.509658467

-0.002658467

-0.440401509

93.75

1.133

c)

99.92% of the variation in viscosity is explained for by in the quadratic model.

SUMMARY OUTPUT

Regression Statistics

Multiple R

0.980

R Square

0.960

Adjusted R Square

0.954

Standard Error

0.047

Observations

8

ANOVA

df

SS

MS

F

Significance F

Regression

1

0.325

0.325

144.727

0.000

Residual

6

0.013

0.002

Total

7

0.339

Coefficients

Standard Error

t Stat

P-value

Lower 95%

Upper 95%

Intercept

1.281

0.047

27.350

0.000

1.167

1.396

Temperature

-0.009

0.001

-12.030

0.000

-0.011

-0.007

RESIDUAL OUTPUT

PROBABILITY OUTPUT

Observation

Predicted Viscosity

Residuals

Standard Residuals

Percentile

Viscosity

1

1.063365838

0.069634162

1.586089461

6.25

0.507

2

0.974890315

0.002109685

0.048053272

18.75

0.542

3

0.888166783

-0.035166783

-0.801010041

31.25

0.602

4

0.798815264

-0.043815264

-0.998000505

43.75

0.672

5

0.710339742

-0.038339742

-0.873281993

56.25

0.755

6

0.622740214

-0.020740214

-0.472409427

68.75

0.853

7

0.535140686

0.006859314

0.156237755

81.25

0.977

8

0.447541159

0.059458841

1.354321478

93.75

1.133