Question

In: Statistics and Probability

Data: (if needed) Race   Position   Oral exam results   Written exam results   Combined results B   Lieutenant   45.83  ...

Data: (if needed)

Race   Position   Oral exam results   Written exam results   Combined results
B   Lieutenant   45.83   46   45.932
B   Lieutenant   52.92   49   50.568
B   Captain   54.76   49   51.304
H   Lieutenant   48.33   58   54.132
B   Lieutenant   52.08   56   54.432
H   Lieutenant   40.83   64   54.732
B   Captain   60   53   55.8
W   Captain   53.81   58   56.324
B   Lieutenant   58.75   55   56.5
W   Lieutenant   54.58   58   56.632
B   Lieutenant   55.83   58   57.132
W   Lieutenant   45.42   65   57.168
H   Lieutenant   44.17   66   57.268
H   Captain   42.86   67   57.344
W   Lieutenant   44.58   66   57.432
W   Lieutenant   51.25   62   57.7
W   Lieutenant   57.92   58   57.968
B   Captain   70.48   50   58.192
B   Lieutenant   60.83   58   59.132
H   Lieutenant   46.25   68   59.3
H   Captain   57.14   61   59.456
W   Lieutenant   60   60   60
W   Lieutenant   49.58   67   60.032
B   Lieutenant   51.25   66   60.1
B   Lieutenant   55   64   60.4
B   Captain   67.62   56   60.648
H   Lieutenant   51.25   67   60.7
H   Lieutenant   42.5   73   60.8
W   Captain   48.57   69   60.828
B   Lieutenant   56.25   64   60.9
B   Lieutenant   56.67   64   61.068
W   Lieutenant   56.25   66   62.1
H   Captain   58.57   65   62.428
H   Lieutenant   50.42   71   62.768
W   Lieutenant   71.67   57   62.868
W   Captain   55.24   68   62.896
H   Lieutenant   51.67   71   63.268
B   Lieutenant   69.17   60   63.668
H   Lieutenant   57.5   70   65
W   Lieutenant   50.42   75   65.168
B   Lieutenant   66.25   65   65.5
W   Lieutenant   55   73   65.8
H   Captain   67.14   65   65.856
H   Lieutenant   56.25   73   66.3
W   Lieutenant   79.17   59   67.068
B   Captain   52.38   77   67.152
W   Lieutenant   64.58   69   67.232
B   Lieutenant   70.83   65   67.332
W   Captain   57.14   75   67.856
W   Lieutenant   51.67   79   68.068
H   Lieutenant   62.5   72   68.2
W   Lieutenant   51.25   80   68.5
W   Lieutenant   73.75   66   69.1
W   Lieutenant   58.75   76   69.1
H   Lieutenant   70.83   68   69.132
H   Captain   60.48   75   69.192
W   Captain   59.05   76   69.22
W   Captain   71.43   68   69.372
W   Captain   71.43   68   69.372
W   Lieutenant   64.58   73   69.632
W   Captain   78.57   64   69.828
W   Captain   62.38   75   69.952
W   Lieutenant   71.67   69   70.068
W   Lieutenant   73.75   68   70.3
B   Captain   70.95   70   70.38
W   Lieutenant   77.5   66   70.6
H   Lieutenant   53.75   82   70.7
W   Lieutenant   65.83   74   70.732
W   Lieutenant   58.33   79   70.732
H   Lieutenant   69.17   72   70.868
H   Lieutenant   55   82   71.2
W   Captain   56.67   81   71.268
W   Captain   82.38   64   71.352
B   Captain   68.57   74   71.828
W   Lieutenant   73.33   71   71.932
W   Lieutenant   72.5   72   72.2
B   Lieutenant   92.08   59   72.232
W   Lieutenant   66.67   76   72.268
B   Lieutenant   70.83   74   72.732
W   Lieutenant   78.33   70   73.332
W   Captain   70   76   73.6
W   Captain   73.33   74   73.732
B   Lieutenant   65.83   80   74.332
W   Lieutenant   87.5   66   74.6
B   Captain   82.38   70   74.952
W   Captain   76.67   74   75.068
W   Lieutenant   63.33   83   75.132
W   Captain   73.81   77   75.724
W   Lieutenant   74.17   77   75.868
B   Lieutenant   80.42   73   75.968
H   Captain   79.05   74   76.02
B   Lieutenant   61.25   86   76.1
W   Captain   80   74   76.4
W   Captain   87.62   69   76.448
B   Lieutenant   77.5   76   76.6
W   Lieutenant   58.75   89   76.9
W   Captain   84.29   72   76.916
W   Lieutenant   73.75   81   78.1
W   Captain   73.81   81   78.124
H   Captain   70   84   78.4
W   Lieutenant   69.58   86   79.432
W   Captain   76.19   82   79.676
H   Captain   76.19   82   79.676
W   Captain   76.19   84   80.876
W   Captain   88.57   76   81.028
W   Lieutenant   68.33   91   81.932
W   Lieutenant   63.75   95   82.5
W   Lieutenant   80.83   84   82.732
W   Lieutenant   73.33   89   82.732
W   Lieutenant   73.75   91   84.1
W   Lieutenant   80   87   84.2
W   Lieutenant   85   84   84.4
W   Captain   82.38   87   85.152
W   Lieutenant   77.5   91   85.6
W   Lieutenant   87.5   87   87.2
W   Captain   80   95   89
W   Lieutenant   88.75   91   90.1
W   Captain   89.52   95   92.808

Test whether the combined test scores for the Lieutenant exam are the same for all the three races at the 5% significance level.

Test statistic, F: 8.58, 12.09, 6.84, or 8.01? (select one)

P-value: 0.004, 0.963, 0.084, or 0.027? (select one)

Conclusion: A. Reject the null hypothesis. There is sufficient evidence that at least one mean combined score is different between races.

B. Reject the null hypothesis. There is insufficient evidence that at least one mean combined score is different between races.

C. Fail to reject the null hypothesis. There is sufficient evidence that at least one mean combined score is different between races.

D. Fail to reject the null hypothesis. There is insufficient evidence that at least one mean combined score is different between races.

Solutions

Expert Solution

Following is the data set for combined results for Lieutenant for different races:

B H W
45.932 54.132 56.632
50.568 54.732 57.168
54.432 57.268 57.432
56.5 59.3 57.7
57.132 60.7 57.968
59.132 60.8 60
60.1 62.768 60.032
60.4 63.268 62.1
60.9 65 62.868
61.068 66.3 65.168
63.668 68.2 65.8
65.5 69.132 67.068
67.332 70.7 67.232
72.232 70.868 68.068
72.732 71.2 68.5
74.332 69.1
75.968 69.1
76.1 69.632
76.6 70.068
70.3
70.6
70.732
70.732
71.932
72.2
72.268
73.332
74.6
75.132
75.868
76.9
78.1
79.432
81.932
82.5
82.732
82.732
84.1
84.2
84.4
85.6
87.2
90.1

Following is the output generated by excel:

One factor ANOVA
Mean n Std. Dev
63.7173 19 9.07690 B
63.6245 15 5.76888 H
71.8433 43 9.14592 W
68.2371 77 9.40928 Total
ANOVA table
Source SS    df MS F    p-value
Treatment 1,266.47361 2 633.236807 8.58 .0004
Error 5,462.15146 74 73.812858
Total 6,728.62508 76

That is,

Test statistics: F = 8.58

The p-value: 0.0004

Since p-value is less than 0.05 so we reject the null hypothesis.

Correct option is:

A. Reject the null hypothesis. There is sufficient evidence that at least one mean combined score is different between races.


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