In: Statistics and Probability
Chapin Manufacturing Company operates 24 hours a day, five days a week. The workers rotate shifts each week. Management is interested in whether there is a difference in the number of units produced when the employees work on various shifts. A sample of five workers is selected and their output recorded on each shift. At the 0.05 significance level, can we conclude there is a difference in the mean production rate by shift or by employee?
| Units Produced | |||
| Employee | Day | Afternoon | Night |
| Skaff | 31 | 38 | 34 |
| Lum | 37 | 35 | 39 |
| Clark | 38 | 27 | 37 |
| Treece | 35 | 28 | 26 |
| Morgan | 22 | 21 | 21 |
Step.1 Enter data in excel sheet.
Step.2 Go to 'Data' menu ---> 'Data Analysis' ---> Select 'ANOVA : Two Factor without replication'.
Step.3 New window pop-up on screen. Provide input and output range.
Excel output:
| Employee | Day | Afternoon | Night | Anova: Two-Factor Without Replication | |||||||
| Skaff | 31 | 38 | 34 | ||||||||
| Lum | 37 | 35 | 39 | SUMMARY | Count | Sum | Average | Variance | |||
| Clark | 38 | 27 | 37 | Skaff | 3 | 103 | 34.33333 | 12.33333 | |||
| Treece | 35 | 28 | 26 | Lum | 3 | 111 | 37 | 4 | |||
| Morgan | 22 | 21 | 21 | Clark | 3 | 102 | 34 | 37 | |||
| Treece | 3 | 89 | 29.66667 | 22.33333 | |||||||
| Morgan | 3 | 64 | 21.33333 | 0.333333 | |||||||
| Day | 5 | 163 | 32.6 | 42.3 | |||||||
| Afternoon | 5 | 149 | 29.8 | 45.7 | |||||||
| Night | 5 | 157 | 31.4 | 58.3 | |||||||
| ANOVA | |||||||||||
| Source of Variation | SS | df | MS | F | P-value | F crit | |||||
| Rows | 452.9333 | 4 | 113.2333 | 6.84879 | 0.010689 | 3.837853 | |||||
| Columns | 19.73333 | 2 | 9.866667 | 0.596774 | 0.57336 | 4.45897 | |||||
| Error | 132.2667 | 8 | 16.53333 | ||||||||
| Total | 604.9333 | 14 |
Test statistic, for employee F= 6.85 and p-value = 0.01
Since p-value is less than 0.05 we reject null hypothesis that mean production rate by employee is same.
Test statistic, for shif F= 0.596 and p-value = 0.57
Since p-value is greater than 0.05 we accept null hypothesis that mean production rate by shift is same.