In: Statistics and Probability
The National Football League (NFL) holds its annual draft of the nation's best college football players in April each year. Prior to the draft, various sporting news services project the players who will be drafted along with the order in which each will be selected in what are called mock drafts. Players who are considered to have superior potential as professional football players are selected earlier in the draft. Suppose the following table shows projections by one mock draft service of what position in the first round players from the Atlantic Coast Conference, the Big Ten Conference, the PAC-12 Conference, and the Southeastern Conference will be selected.
ACC | Big Ten | PAC-12 | SEC | ||||
---|---|---|---|---|---|---|---|
College Attended |
Projected Draft Position |
College Attended |
Projected Draft Position |
College Attended |
Projected Draft Position |
College Attended |
Projected Draft Position |
Florida State | 4 | Iowa | 8 | USC | 3 | Florida | 1 |
Clemson | 5 | Michigan St | 10 | Oregon | 7 | Alabama | 2 |
Miami | 6 | Nebraska | 11 | Oregon | 15 | Kentucky | 9 |
Georgia Tech | 13 | Minnesota | 26 | Washington | 16 | Texas A&M | 12 |
Louisville | 19 | Wisconsin | 27 | UCLA | 17 | Missouri | 14 |
Wake Forest | 20 | UCLA | 21 | Alabama | 18 | ||
Florida State | 23 | Stanford | 22 | LSU | 25 | ||
Virginia Tech | 28 | Arizona St | 24 | LSU | 29 |
Use the Kruskal-Wallis test to determine if there is any difference among NFL teams for players from these four conferences. Use α = 0.05.
State the null and alternative hypotheses.
Find the value of the test statistic. (Round your answer to two decimal places.)
What is the p-value? (Round your answer to three decimal places.)
p-value =
What is your conclusion?
Reject H0. There is sufficient evidence to conclude that there is a significant difference among NFL teams for players from these four conferences.
Reject H0. There is not sufficient evidence to conclude that there is a significant difference among NFL teams for players from these four conferences.
Do not reject H0. There is not sufficient evidence to conclude that there is a significant difference among NFL teams for players from these four conferences.
Do not reject H0. There is sufficient evidence to conclude that there is a significant difference among NFL teams for players from these four conferences.
ACC | Big Ten | PAC-12 | SEC | ||||
---|---|---|---|---|---|---|---|
College Attended |
Projected Draft Position |
College Attended |
Projected Draft Position |
College Attended |
Projected Draft Position |
College Attended |
Projected Draft Position |
Florida State | 3 | Iowa | 9 | USC | 4 | Florida | 1 |
Clemson | 5 | Michigan St | 10 | Oregon | 6 | Alabama | 2 |
Miami | 8 | Nebraska | 11 | Oregon | 15 | Kentucky | 7 |
Georgia Tech | 13 | Minnesota | 26 | Washington | 17 | Texas A&M | 12 |
Louisville | 18 | Wisconsin | 27 | UCLA | 19 | Missouri | 14 |
Wake Forest | 20 | UCLA | 21 | Alabama | 16 | ||
Florida State | 23 | Stanford | 22 | LSU | 25 | ||
Virginia Tech | 29 | Arizona St | 24 | LSU | 28 |
Find the value of the test statistic. (Round your answer to two decimal places.)
What is the p-value? (Round your answer to three decimal places.)
p-value =
Sample 1 | Sample 2 | Sample 3 | Sample 4 |
4 | 8 | 3 | 1 |
5 | 10 | 7 | 2 |
6 | 11 | 15 | 9 |
13 | 26 | 16 | 12 |
19 | 27 | 17 | 14 |
20 | 21 | 18 | |
23 | 22 | 25 | |
28 | 24 | 29 |
Assign rank to the values taking all the samples as one sample.
Rank for sample 1 | Rank for sample 2 | Rank for sample 3 | Rank for sample 4 |
4 | 8 | 3 | 1 |
5 | 10 | 7 | 2 |
6 | 11 | 15 | 9 |
13 | 26 | 16 | 12 |
19 | 27 | 17 | 14 |
20 | 21 | 18 | |
23 | 22 | 25 | |
28 | 24 | 29 |
N = 29
n1 = 8
n2 = 5
n3 = 8
n4 = 8
With the information provided we can now easily compute the sum of ranks for each of the samples:
Sum of Rank for Sample 1 = 118
Sum of Rank for Sample 2 = 82
Sum of Rank for Sample 3 = 125
Sum of Rank for Sample 4 = 110
Null and Alternative hypothesis:
Ho: The samples come from populations with equal medians
Ha: The samples come from populations with medians that are not all equal
Test statistic:
H = (12/(N*(N+1))) * (R1²/n1 + R2²/n2 +….+ Rk²/nk) - 3(N+1) = (12/(29*(29+1) * (118²/8 + 82²/5 + 125²/8 + 110²/8) - 3(29+1) = 0.358
df = n-13
p-value = CHISQ.DIST.RT(0.3576, 3) = 0.949
Conclusion:
p-value > α, Do not reject the null hypothesis
Do not reject H0. There is not sufficient evidence to conclude that there is a significant difference among NFL teams for players from these four conferences.
-----------------------------
Q2:
Sample 1 | Sample 2 | Sample 3 | Sample 4 |
3 | 9 | 4 | 1 |
5 | 10 | 6 | 2 |
8 | 11 | 15 | 7 |
13 | 26 | 17 | 12 |
18 | 27 | 19 | 14 |
20 | 21 | 16 | |
23 | 22 | 25 | |
29 | 24 | 28 |
Rank for sample 1 | Rank for sample 2 | Rank for sample 3 | Rank for sample 4 |
3 | 9 | 4 | 1 |
5 | 10 | 6 | 2 |
8 | 11 | 15 | 7 |
13 | 26 | 17 | 12 |
18 | 27 | 19 | 14 |
20 | 21 | 16 | |
23 | 22 | 25 | |
29 | 24 | 28 |
N = 29
n1 = 8
n2 = 5
n3 = 8
n4 = 8
With the information provided we can now easily compute the sum of ranks for each of the samples:
Sum of Rank for Sample 1 = 119
Sum of Rank for Sample 2 = 83
Sum of Rank for Sample 3 = 128
Sum of Rank for Sample 4 = 105
Null and Alternative hypothesis:
Ho: The samples come from populations with equal medians
Ha: The samples come from populations with medians that are not all equal
Test statistic:
H = (12/(N*(N+1))) * (R1²/n1 + R2²/n2 +….+ Rk²/nk) - 3(N+1) = (12/(29*(29+1) * (119²/8 + 83²/5 + 128²/8 + 105²/8) - 3(29+1) = 0.677
df = n-13
p-value = CHISQ.DIST.RT(0.6766, 3) = 0.879
Conclusion:
p-value > α, Do not reject the null hypothesis