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17. The director of human resources for a large bank has compiled data on about

ID: 3356671 • Letter: 1

Question

17. The director of human resources for a large bank has compiled data on about 70 former employees at one of the bank's call centers (see the Excel file Cal Center Data). For each of the following, assume equal variances of the two populations a. Test the null hypothesis that the average length of service for males is the same as for females. b. Test the null hypothesis that the average length of service for individuals without prior call center experience is the same as those with experience Test the nuli hypothesis that the average length of service for individuals with a college degree is the c. same as for individuals without a college degree.

Explanation / Answer

a)

Males

Females

3.47

7.02

1.78

2.07

4.42

3.05

3.29

2.95

0.49

2.15

0.61

4.03

3.12

2.15

3.53

1.94

2.47

2.91

3.27

3.02

1.1

2.53

1.78

1.84

2.88

0.98

2.2

2.3

1.44

2.05

2.53

2.13

1.41

1.7

1.08

2.11

0.63

2.15

1.3

1.95

2.13

1.02

2.12

1.26

2.16

1.64

2.04

1.48

1.75

1.31

2.12

1.16

0.37

1.05

1.04

1.24

1.75

0.81

1.71

0.99

1.29

1

1.46

0.57

1.88

1.5

1.16

2

0.96

1

0.87

0.76

0.35

2

0.76

1.787

1.973142857

Mean

0.972934235

1.16451649

SD

H0: 1 - 2 = 0 i.e. (1 = 2)

H1: 1 - 2 0 i.e. (1 2)

            

Assuming population variances are equal, we would have to calculate pooled-variance t-Test keeping males as population 1 and females as population 2

Sp^2= (n1-1)S1^2+(n2-1)S2^2/(n1-1)+(n2-1)

         = (40-1)*0.97^2+(35-1)*1.1645^2/39+34

         = 36.91744+46.1073543/73

         = 1.1373

tSTAT=(X1-X2)-(µ1-µ2)/Sp^2(1/n1+1/n2)

       =(1.787-1.973)-0/1.1373(1/40+1/35)

       =-0.186/0.2468

       =-0.75

tCRIT is +/- 1.99 and hence cannot reject the null hypothesis

b)

No Prior Exp

Prior Exp

7.02

3.47

2.07

4.42

1.78

3.29

3.12

3.05

2.95

0.49

4.03

0.61

3.53

2.15

2.47

2.91

2.15

3.02

3.27

2.53

1.1

2.88

1.78

0.98

1.94

0.63

1.84

2.13

2.2

2.3

1.44

2.05

2.53

2.13

1.41

2.12

1.08

2.12

1.3

1.75

2.16

1.71

2.04

1.48

1.7

1.88

2.11

1.24

1.75

0.87

2.15

0.99

0.37

0.76

1.95

0.35

1.02

0.57

1.26

2

1.04

0.76

1.64

2

1.29

1

1.31

1.46

1.16

1.16

1.05

0.96

0.81

1

1.5

1.902380952

1.837575758

Mean

1.118591906

1.004564677

SD

H0: 1 - 2 = 0 i.e. (1 = 2)

H1: 1 - 2 0 i.e. (1 2)

            

Assuming population variances are equal, we would have to calculate pooled-variance t-Test keeping people with No Prior Exp as population 1 and With Prior Exp as population 2

Sp^2= (n1-1)S1^2+(n2-1)S2^2/(n1-1)+(n2-1)

         = (42-1)*1.12^2+(33-1)*1.0045^2/41+32

         = 51.30+32.29/73

         = 1.145

tSTAT=(X1-X2)-(µ1-µ2)/Sp^2(1/n1+1/n2)

       =(1.90-1.8375)-0/1.145(1/42+1/33)

       =0.0625/0.2489

       =0.25

tCRIT is +/- 1.99 and hence cannot reject the null hypothesis

c)

With college degree

Without college degree

1.78

7.02

0.49

3.47

0.61

2.07

3.12

4.42

2.95

3.29

2.15

3.05

1.1

4.03

1.78

3.53

1.84

2.47

1.44

2.15

1.41

3.27

1.08

1.94

0.98

2.91

0.63

3.02

1.3

2.53

2.13

2.88

2.05

2.2

2.13

2.53

2.12

2.3

2.16

2.04

1.75

1.7

2.15

2.11

0.37

2.12

1.26

1.95

1.64

1.02

1.71

1.04

1.31

1.75

1.16

1.29

1.05

1.48

0.96

1.46

0.81

1.88

0.87

1.16

0.76

1.24

0.35

0.99

0.57

1

2

1.5

0.76

1

2

1.440263158

2.319189189

Mean

0.689980363

1.196927498

SD

H0: 1 - 2 = 0 i.e. (1 = 2)

H1: 1 - 2 0 i.e. (1 2)

            

Assuming population variances are equal, we would have to calculate pooled-variance t-Test keeping people with college degree as population 1 and Without college degree as population 2

Sp^2= (n1-1)S1^2+(n2-1)S2^2/(n1-1)+(n2-1)

         = (38-1)*0.69^2+(37-1)*1.1969^2/37+36

         = 17.61+51.57/73

         = 0.9478

tSTAT=(X1-X2)-(µ1-µ2)/Sp^2(1/n1+1/n2)

       =(0.4760-1.4326)-0/0.9478(1/38+1/37)

       =-0.878926/0.22485206

       =-3.91

tCRIT is +/- 1.99 and hence        reject the null hypothesis

Males

Females

3.47

7.02

1.78

2.07

4.42

3.05

3.29

2.95

0.49

2.15

0.61

4.03

3.12

2.15

3.53

1.94

2.47

2.91

3.27

3.02

1.1

2.53

1.78

1.84

2.88

0.98

2.2

2.3

1.44

2.05

2.53

2.13

1.41

1.7

1.08

2.11

0.63

2.15

1.3

1.95

2.13

1.02

2.12

1.26

2.16

1.64

2.04

1.48

1.75

1.31

2.12

1.16

0.37

1.05

1.04

1.24

1.75

0.81

1.71

0.99

1.29

1

1.46

0.57

1.88

1.5

1.16

2

0.96

1

0.87

0.76

0.35

2

0.76

1.787

1.973142857

Mean

0.972934235

1.16451649

SD

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