In: Statistics and Probability
The number of emails arriving at a server per minute is claimed to follow a Poisson distribution. To test this claim, the number of emails arriving in 70 randomly chosen 1-minute intervals is recorded. The table below summarizes the result.
Number of emails | 0 | 1 | 2 | ≥ 3 |
Observed Frequency | 13 | 22 | 23 | 12 |
Test the hypothesis that the number of emails per minute follows a Poisson distribution? Use a significance level of α = 0.05.
H0: Null Hypothesis: X follows Poisson Distribution
HA: Alternative Hypothesis: X does not follow Poisson Distribution
Mean of Poisson Distribution is got as follows:
So,
E0= 0.2263 X 70 = 15.841
So,
E1= 0.3363 X 70 = 23.541
So,
E2= 0.2498 X 70 = 17.485
So,
E3= 0.1876 X 70 = 13.132
Test Statistic is got as follows:
Observed (O) | Expected (E) | (O - E)2/E |
13 | 15.841 | 0.5095 |
22 | 23.541 | 0.1009 |
23 | 17.485 | 1.7395 |
12 | 13.133 | 0.0977 |
Total = = | 2.448 |
Nuber of Degrees of Freedom = 4 - 1 - 1 = 2
By Technology, P - Value = 0.2941
Since p value is greater than , the difference is not significant. Fail to reject null hypothesis.
Conclusion:
the number of emails per minute follows a Poisson distribution