In: Statistics and Probability
An obstetrician wanted to determine whether the mean number of births was the same for each of the five days of the week. She randomly selected eight days for each of the five weekdays and recorded the number of births on that day in the data table below. Refer to the ANOVA results from Excel.
Monday |
Tuesday |
Wednesday |
Thursday |
Friday |
10023 10265 10283 10456 10691 11189 11198 11465 |
11045 11621 11753 11944 12509 12577 12927 13521 |
11346 11084 11593 11570 11216 12193 11875 11818 |
12023 11171 11903 11745 11233 12132 12433 12543 |
11749 11545 11627 12321 11624 12422 12192 12543 |
SUMMARY
Groups |
Count |
Sum |
Average |
Variance |
Monday |
8 |
85570 |
10696.25 |
279042.5 |
Tuesday |
8 |
97897 |
12237.13 |
633537.8 |
Wednesday |
8 |
92695 |
11586.88 |
136085.3 |
Thursday |
8 |
95183 |
11897.88 |
252402.7 |
Friday |
8 |
96023 |
12002.88 |
166186.1 |
ANOVA
Source Of Variation |
SS |
df |
MS |
F |
P-Value |
F Crit |
Between Groups |
11507633 |
4 |
2876908 |
9.803713 |
1.99E-05 |
2.641465 |
Within Groups |
10270781 |
35 |
293450.9 |
|||
Total |
21778414 |
39 |
a) Test the hypothesis that the mean number of births for each weekday is the same at the ? = 0.01 level of significance. Use the p-value method.
Please show thorough steps for hypothesis test I am having trouble understanding this.
H0: Null Hypothesis: ( the mean number of births was the same for each of the five days of the week) (Claim)
HA: Alternative Hypothesis: (At least one mean is different from other 4 means) ( the mean number of births was not the same for each of the five days of the week)
From the given data, the following Table is calculated:
Monday | Tuesday | Wednesday | Thursday | Friday | Total | |
N | 8 | 8 | 8 | 8 | 8 | 40 |
85570 | 97897 | 92695 | 95183 | 96023 | 467368 | |
Mean | 85570/8=10696.25 | 97897/8=12237.125 | 92695/8=11586.875 | 95183/8=11897.875 | 96023/8=12002.875 | 467368/40=11684.2 |
Std. Dev. | 528.2447 | 795.9509 | 368.8974 | 502.397 | 407.6593 | 747.2756 |
From the above Table, ANOVA Table is calculated as follows:
Source of Variation | Sum of Squares | Degrees of Fredom | Mean Square | F | P - Value | F Crit |
Between groups | 11507633.4 | 4 | 11507633.4/4 = 2876908.35 | 2876908.35/ 293450.8857 = 9.8037 | 0.00002 | 2.641465 |
Within groups | 10270781 | 35 | 10270781/ 35 = 293450.8857 | |||
Total | 21778414.4 | 39 |
F Ratio Value = 2876908.35/ 293450.8857 = 9.8037
Degtrees of Freedom for Numerator =4
Degrees of Freedom for denominaor = 35
By Technology, p - value = 0.00002
Since p - value = 0.00002 is less than = 0.01, the difference is significant. Reject null hypothesis.
Conclusion:
The data do not support the clam that the mean number of births was
the same for each of the five days of the week.
= 0.01
Degtrees of Freedom for Numerator =4
Degrees of Freedom for denominaor = 35
By Technology, critical value of F = 2.641465.
Since calculated value of F = 9.8037 is greater than critical value of F = 2.641465., the difference is significant. Reject null hypothesis.
Conclusion:
The data do not support the clam that the mean number of births was
the same for each of the five days of the week.