In: Statistics and Probability
We anticipate that deadly two vehicle motorcycle accidents occur at the same frequency on all seven days of the week. However, is this true? The table shows the number of two-vehicle crashes including a motorbike and a passenger vehicle, with day of week, in a random sample of 1,792 accidents
Day |
Freq |
Relative Frequency |
Sunday |
329 |
0.18 |
Monday |
205 |
0.11 |
Tuesday |
202 |
0.11 |
Wednesday |
194 |
0.11 |
Thursday |
193 |
0.11 |
Friday |
273 |
0.15 |
Saturday |
396 |
0.22 |
Total |
1792 |
1.0 |
A.What is the null and the alternative hypothesis.
B.Find the χ2 statistic and the degrees of freedom.
C.Use the critical value way to find the P-value with a significance level of α=0.05
D.What is the conclusion
A.
Null Hypothesis H0: The deadly two vehicle motorcycle accidents occur at the same frequency on all seven days of the week.
Alternative Hypothesis Ha: The deadly two vehicle motorcycle accidents does not occur at the same frequency on all seven days of the week.
B.
Proportion of motorcycle accidents at any given day, p = 1/7
Expected frequency of accidents at each day, E = np = 1792 / 7 = 256
= (329 - 256)^2 / 256 + (205 - 256)^2 / 256 + (202 - 256)^2 / 256 + (194 - 256)^2 / 256 + (193 - 256)^2 / 256 + (273 - 256)^2 / 256 + (396 - 256)^2 / 256
= 150.5781
Degree of freedom = Number of groups - 1 = 7 - 1 = 6
C.
Critical value of Chi Square statistic at α=0.05 and df = 6 is 12.59
Since observed chi square test statistic (150.5781) is greater than the critical value (12.59), P-value < 0.05
D.
We reject null hypothesis H0 and conclude that there is significant evidence that the deadly two vehicle motorcycle accidents does not occur at the same frequency on all seven days of the week.