REGRESSION ANALYSIS AND CRITICAL APPRAISAL

Regression Analysis and Critical Appraisal

Regression Analysis and Critical Appraisal

Multivariate Analysis

(a) Using a multiple regression analysis explore the effects of the independent variables on TIME 1.

Descriptive Statistics

Mean

Std. Deviation

N

time1

99.69

105.697

252

group

1.50

.501

252

enthusiasm for task

2.50

1.120

252

age

21.81

4.151

252

gender

1.38

.486

252

hand2

1.68

.468

252

dumgroup

.50

.501

252

The result of the descriptive chart is showing the mean of the dependent variable that is the first trial after drinking of coffee or decaffeinated substitute is 99.69 and standard deviation is 105.69, and the mean and standard deviation of independent variables are also mentioned in the above table.

Model Summaryb

Model

R

R Square

Adjusted R Square

Std. Error of the Estimate

Change Statistics

R Square Change

F Change

df1

df2

Sig. F Change

1

.404a

.163

.146

97.652

.163

9.612

5

246

.000

a. Predictors: (Constant), dumgroup, gender, hand2, enthusiasm for task, age

b. Dependent Variable: time1

ANOVAb

Model

Sum of Squares

df

Mean Square

F

Sig.

1

Regression

458281.756

5

91656.351

9.612

.000a

Residual

2345849.716

246

9535.974

Total

2804131.472

251

a. Predictors: (Constant), dumgroup, gender, hand2, enthusiasm for task, age

b. Dependent Variable: time1

The above charts are showing that the significant value of ANOVA table is less than 0.05 and the value of R is 40.4 % and the value of R-square is 16.3 % that means there is a relationship between the dependent variable that is the first trial after drinking of coffee or decaffeinated substitute and the independent variables.

Coefficientsa

Model

Un-standardized Coefficients

Standardized Coefficients

t

Sig.

Collinearity Statistics

B

Std. Error

Beta

Tolerance

VIF

1

(Constant)

14.205

38.627

.368

.713

enthusiasm for task

6.594

5.688

.070

1.159

.247

.936

1.069

age

-4.670

1.626

-.183

-2.872

.004

.834

1.199

gender

77.153

13.222

.354

5.835

.000

.922

1.085

hand2

26.755

13.925

.118

1.921

.056

.895

1.118

dumgroup

39.122

12.723

.185

3.075

.002

.935

1.069

a. Dependent Variable: time1

From the above table, it can be understood that there is not too much multicolinearity between the variables because the values of tolerance and VIF are near to 1 which is a good indication. Moreover the beta values of all the independent variables are positive, but age is in negative that shows there is a negative relationship of the first trial after drinking of coffee with the age. However, there is a positive relationship between the first trials of coffee with the other independent variables (Keith, 2006, pp. 12-32).

(b) Using a multiple regression analysis explore the effects of the independent variables on TIME 10.

Descriptive Statistics

Mean

Std. Deviation

N

time10

9.21

4.792

252

group

1.50

.501

252

enthusiasm for task

2.50

1.120

252

age

21.81

4.151

252

gender

1.38

.486

252

hand2

1.68

.468

252

dumgroup

.50

.501

252

The result of the descriptive chart is showing the mean of the dependent variable that is third trial after drinking of coffee or decaffeinated substitute is 9.21 and standard deviation is 4.79, and the mean and standard deviation of independent variables also mentioned in the above table.

Model Summaryb

Model

R

R Square

Adjusted R Square

Std. Error of the Estimate

Change Statistics

R Square Change

F Change

df1

df2

Sig. F Change

1

.439a

.193

.176

4.349

.193

11.748

5

246

.000

a. Predictors: (Constant), dumgroup, gender, hand2, enthusiasm for task, age

b. Dependent Variable: time10

ANOVAb

Model

Sum of Squares

df

Mean Square

F

Sig.

1

Regression

1110.868

5

222.174

11.748

.000a

Residual

4652.402

246

18.912

Total

5763.270

251

a. Predictors: (Constant), dumgroup, gender, hand2, enthusiasm for task, age

b. Dependent Variable: time10

The above charts are showing that the significant value of ANOVA table is less than 0.05 and the value of R is 43.9 % and the value of R-square is 194.3 % that means there is a relationship between the dependent variable that is the third trial after drinking of coffee or decaffeinated substitute and the independent variables.

Coefficientsa

Model

Unstandardized Coefficients

Standardized Coefficients

t

Sig.

Collinearity Statistics

B

Std. Error

Beta

Tolerance

VIF

1

(Constant)

4.677

1.720

2.719

.007

enthusiasm for task

.318

.253

.074

1.254

.211

.936

1.069

age

.372

.072

.322

5.135

.000

.834

1.199

gender

-3.374

.589

-.342

-5.731

.000

.922

1.085

hand2

-.109

.620

-.011

-.176

.861

.895

1.118

dumgroup

.898

.567

.094

1.585

.114

.935

1.069

a. Dependent Variable: time10

From the above table, it can be understood that there is not too much multicolinearity between the variables because the values of tolerance and VIF are near to 1 which is a good indication (Cohen, 2003, pp. ...