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Oxnard Petro, Ltd., has three interdisciplinary project development teams that f

ID: 3128192 • Letter: O

Question

Oxnard Petro, Ltd., has three interdisciplinary project development teams that function on an ongoing basis. Team members rotate from time to time. Every 4 months (three times a year) each department head rates the performance of each project team (using a 0 to 100 scale, where 100 is the best rating). Are the main effects significant? Is there an interaction?

  

Fill in the missing data. (Round your Table of Means values to 1 decimal place, SS and F values to 2 decimal places, MS values to 3 decimal places and p-value to 4 decimal places.)

Oxnard Petro, Ltd., has three interdisciplinary project development teams that function on an ongoing basis. Team members rotate from time to time. Every 4 months (three times a year) each department head rates the performance of each project team (using a 0 to 100 scale, where 100 is the best rating). Are the main effects significant? Is there an interaction?

Explanation / Answer

Two way ANOVA

Oxnard Petro, Ltd., has three interdisciplinary project development teams that function on an ongoing basis. Team members rotate from time to time. Every 4 months (three times a year) each department head rates the performance of each project team (using a 0 to 100 scale, where 100 is the best rating). Are the main effects significant? Is there an interaction?

Solution

Here, we have to test the hypothesis whether there is significant main effects and interaction in the scores of the three interdisciplinary projects in the three years. For checking this claim, we have to use the two way analysis of variance. First of all, we need to arrange the data in a following manner.

Score

Year

Discipline

86

2007

Marketing

85

2007

Marketing

82

2007

Marketing

85

2009

Marketing

81

2009

Marketing

80

2009

Marketing

82

2011

Marketing

82

2011

Marketing

81

2011

Marketing

78

2007

Engineering

84

2007

Engineering

79

2007

Engineering

83

2009

Engineering

76

2009

Engineering

77

2009

Engineering

79

2011

Engineering

79

2011

Engineering

75

2011

Engineering

86

2007

Finance

89

2007

Finance

91

2007

Finance

91

2009

Finance

88

2009

Finance

93

2009

Finance

91

2011

Finance

99

2011

Finance

81

2011

Finance

The ANOVA test is given as below:

The mean scores for the given three years are given as below:

Year

Average score

2007

84.4

2009

83.8

2011

83.2

The mean scores for the given three interdisciplinary projects are given as below:

Discipline

Average Score

Engineering

78.9

Finance

89.9

Marketing

82.7

The ANOVA table is given as below:

Two-way ANOVA: Score versus Year, Discipline

Analysis of Variance for Score  

Source        DF        SS        MS        F        P

Year           2       6.7       3.4     0.22    0.802

Discipli       2     562.3     281.1    18.65    0.000

Interaction    4      23.7       5.9     0.39    0.811

Error         18     271.3      15.1

Total         26     864.1

For the variable year we get the p-value as 0.802 which is greater than the level of significance 0.05, so we do not reject the hypothesis that there is no any significant effect due to the year. For the variable discipline we get the p-value as 0.00 which is less than the level of significance 0.05, so we reject the null hypothesis that there is no any significant effect due to the discipline. For the combined interaction for the year and discipline, the p-value is given as 0.811 which is greater than the given level of significance 0.05, so we do not reject the null hypothesis that there is no any significant interaction present.

Score

Year

Discipline

86

2007

Marketing

85

2007

Marketing

82

2007

Marketing

85

2009

Marketing

81

2009

Marketing

80

2009

Marketing

82

2011

Marketing

82

2011

Marketing

81

2011

Marketing

78

2007

Engineering

84

2007

Engineering

79

2007

Engineering

83

2009

Engineering

76

2009

Engineering

77

2009

Engineering

79

2011

Engineering

79

2011

Engineering

75

2011

Engineering

86

2007

Finance

89

2007

Finance

91

2007

Finance

91

2009

Finance

88

2009

Finance

93

2009

Finance

91

2011

Finance

99

2011

Finance

81

2011

Finance