In: Statistics and Probability
27) A company manager wishes to test a union leader's claim that absences occur on the different week days with the same frequencies. Use a significance level of 0.01 to test the manager's claim. In a study of absences, 16 occurred on a Monday, 26 occurred on a Tuesday, 38 occurred on a Wednesday, 33 occurred on a Thursday, and 12 occurred on a Friday. Use the p-value method of hypothesis testing.
Given:
A company manager wishes to test a union leader's claim that absences occur on the different week days with the same frequencies.
Days | Monday | Tuesday | Wednesday | Thrusday | Friday |
Absence | 16 | 26 | 38 | 33 | 12 |
Hypothesis test:
H0 : p1 = 1/5, p2 = 1/5, p3 = 1/5, p4 = 1/5, p5 = 1/5
Ha : At least one of the probability not equal to hypothesized value.
Table for calculating test statistics:
Days, x | P(x) | Oi | Ei = n×P(x) | (Oi-Ei)2/Ei |
Monday | 1/5 | 16 | 125×1/5 = 25 | 3.24 |
Tuesday | 1/5 | 26 | 25 | 0.04 |
Wednesday | 1/5 | 38 | 25 | 6.76 |
Thursday | 1/5 | 33 | 25 | 2.56 |
Friday | 1/5 | 12 | 25 | 6.76 |
Total | 1 | 125 | 125 | (Oi-Ei)2/Ei =19.36 |
Test statistics is
2 = (Oi-Ei)2/Ei = 19.36
Degree of freedom, df = 5-1 = 4
P-value corresponding to chi square test statistic 19.36 with degree of freedom = 4 is 0.000668
So P-value = 0.0007
Since P - value is less than significance level 0.01 reject null hypothesis.
Conclusion: Reject H0. There is sufficient evidence to conclude that absences occur on the different week days with the same frequencies.