In soccer, serious fouls in the penalty box result in a penalty kick withone kicker and one defending goalkeeper. The table below summarizes results from 286 kicksduring games among top teams (based on data from “Action Bias Among Elite Soccer Goalkeepers:

The Case of Penalty Kicks,” by Bar-Eli et al., Journal of Economic Psychology,Vol.28, No. 5). In the table, jump direction indicates which way the goalkeeper jumped, where thekick direction is from the perspective of the goalkeeper. Use a 0.05 significance level to test theclaim that the direction of the kick is independent of the direction of the goalkeeper jump. Dothe results support the theory that because the kicks are so fast, goalkeepers have no time toreact, so the directions of their jumps are independent of the directions of the kicks?

Goalkeeper Jump

Left

Center

Right

Kick to Left

54

1

37

Kick to Center

41

10

31

Kick to Right

46

7

59

Short Answer

Expert verified

The direction of the kick is dependent on the direction of the goalkeeper’s jump. Thus, the result is supportive of the theory.

Step by step solution

01

Given information

The data for the direction of kicks and the goalkeeper’s jump is recorded.

The level of significance is 0.05.

02

Compute the expected frequencies

Theexpected frequencyis computed as,

\(E = \frac{{\left( {{\rm{row}}\;{\rm{total}}} \right)\left( {{\rm{column}}\;{\rm{total}}} \right)}}{{\left( {{\rm{grand}}\;{\rm{total}}} \right)}}\)

The table with row and column total is represented as,


Left

Center

Right

Row Total

Kick to Left

54

1

37

92

Kick to Center

41

10

31

82

Kick to Right

46

7

59

112

Column Total

141

18

127

286

Theexpected frequency tableis represented as,


Left

Center

Right

Kick to Left

45.3566

5.7902

40.8531

Kick to Center

40.4266

5.1608

36.4126

Kick to Right

55.2168

7.0490

49.7343

All the expected frequencies are above 5, and hence the requirement for the test is met assuming the sampling is done randomly.

03

State the null and alternate hypothesis

To test the independence of kick direction on goalkeeper’s jump, the hypothesis is formulated as follows:

\({H_0}:\)The direction of the kick is independent of the direction of the goalkeeper jump.

\({H_1}:\)The direction of the kick is dependent of the direction of the goalkeeper jump.

04

Compute the test statistic

The value of the test statisticis computed as,

\[\begin{aligned}{c}{\chi ^2} = \sum {\frac{{{{\left( {O - E} \right)}^2}}}{E}} \\ = \frac{{{{\left( {54 - 45.3566} \right)}^2}}}{{45.3566}} + \frac{{{{\left( {1 - 5.7902} \right)}^2}}}{{5.7902}} + ... + \frac{{{{\left( {59 - 49.7343} \right)}^2}}}{{49.7343}}\\ = 14.5887\\ \approx 14.589\end{aligned}\]

Therefore, the value of the test statistic is 14.589.

05

Compute the degrees of freedom

The degrees of freedomare computed as,

\(\begin{aligned}{c}\left( {r - 1} \right)\left( {c - 1} \right) = \left( {3 - 1} \right)\left( {3 - 1} \right)\\ = 4\end{aligned}\)

Therefore, the degrees of freedom are 4.

06

Compute the critical value

From chi-square table, the critical value for row corresponding to 4 degrees of freedom and at 0.05 level of significance 9.488.

Therefore, the critical value is 9.488.

Also, the p-value is computed as 0.0056

07

State the decision

Since the critical (9.488) is less than the value of test statistic (14.589), in this case, the null hypothesis is rejected.

Therefore, the decision is to reject the null hypothesis.

08

State the conclusion

There isnot sufficient evidence to favour the claimthatthe direction of the kick is independent of the direction of the goalkeeper jump.

Therefore, the result is supportive of the theory that the direction of kicks is dependent to jumps of goalkeeper.

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Most popular questions from this chapter

Questions 6–10 refer to the sample data in the following table, which describes the fate of the passengers and crew aboard the Titanic when it sank on April 15, 1912. Assume that the data are a sample from a large population and we want to use a 0.05 significance level to test the claim that surviving is independent of whether the person is a man, woman, boy, or girl.


Men

Women

Boys

Girls

Survived

332

318

29

27

Died

1360

104

35

18

Is the hypothesis test left-tailed, right-tailed, or two-tailed?

Cybersecurity The accompanying Statdisk results shown in the margin are obtained from the data given in Exercise 1. What should be concluded when testing the claim that the leading digits have a distribution that fits well with Benford’s law?

Questions 6–10 refer to the sample data in the following table, which describes the fate of the passengers and crew aboard the Titanic when it sank on April 15, 1912. Assume that the data are a sample from a large population and we want to use a 0.05 significance level to test the claim that surviving is independent of whether the person is a man, woman, boy, or girl.


Men

Women

Boys

Girls

Survived

332

318

29

27

Died

1360

104

35

18

What distribution is used to test the stated claim (normal, t, F, chi-square, uniform)?

In a study of high school students at least 16 years of age,

researchers obtained survey results summarized in the accompanying table (based on data from “Texting While Driving and Other Risky Motor Vehicle Behaviors Among U.S. High School Students,” by O’Malley, Shults, and Eaton, Pediatrics,Vol. 131, No. 6). Use a 0.05 significance level to test the claim of independence between texting while driving and irregular seat belt use. Are those two risky behaviors independent of each other?


Irregular Seat Belt Use?


Yes

No

Texted while driving

1737

2048

No Texting while driving

1945

2775

Cybersecurity When using the data from Exercise 1 to test for goodness-of-fit with the distribution described by Benford’s law, identify the null and alternative hypotheses.

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