Using Nonparametric Tests. In Exercises 1–10, use a 0.05 significance level with the indicated test. If no particular test is specified, use the appropriate nonparametric test from this chapter.

California Lottery Listed below are consecutive first-digits drawn in the California Daily 4 lottery. Test for randomness of even and odd integers. Does the lottery appear to be working as it should?

5

2

2

8

4

8

8

7

1

0

6

4

1

5

1

5

5

3

1

4

1

5

0

0

3

9

6

6

3

7





Short Answer

Expert verified

There is not enough evidence to warrant rejection of the claim that the sequence of even and oddis random.

Yes, the California lottery appears to be working fine.

Step by step solution

01

Given information

The first digits drawn in a lottery are given.

02

Runs Test for Randomness

This test is used to investigate the randomness of a sequence.

The null hypothesis is as follows:

The sequence of odd and even digits is random.

The alternative hypothesis is as follows:

The sequence of odd and even digits is not random.

03

Test Statistic

The data is arranged in the following manner, symbolizingall odd digits with the letter O and all even digits with the letter E:

Digit

Symbol

Digit

Symbol

5

O

5

O

2

E

5

O

2

E

3

O

8

E

1

O

4

E

4

E

8

E

1

O

8

E

5

O

7

O

0

E

1

O

0

E

0

E

3

O

6

E

9

O

4

E

6

E

1

O

6

E

5

O

3

O

1

O

7

O

The sequence is as follows:

O

E

E

E

E

E

E

O

O

E

E

E

O

O

O

O

O

O

O

E

O

O

E

E

O

O

E

E

O

O

Now, the number of times E occurs is denoted by\({n_1}\)and the number of times O occurs is denoted by\({n_2}\).

Thus,

\(\begin{array}{l}{n_1} = 14\\{n_2} = 16\end{array}\)

The runs of the sequence are formed as follows:

\(\underbrace O_{{1^{st}}run}\underbrace {EEEEEE}_{{2^{nd}}run}\underbrace {OO}_{{3^{rd}}run}\underbrace {EEE}_{{4^{th}}run}\underbrace {OOOOOOO}_{{5^{th}}run}\underbrace E_{{6^{th}}run}\underbrace {OO}_{{7^{th}}run}\underbrace {EE}_{{8^{th}}run}\underbrace {OO}_{{9^{th}}run}\underbrace {EE}_{{{10}^{th}}run}\underbrace {OO}_{{{11}^{th}}run}\)

The number of runs is denoted by G is equal to 11.

Here, \({n_1} < 20\) and \({n_2} < 20\). The value of the test statistic is G.

04

Step 4:Determine the critical value and the conclusion of the test

Referring to Table A-10, the critical values of G at\(\alpha = 0.05\)for\({n_1} = 14\)and\({n_2} = 16\)are 10 and 22.

The value of G falls within the interval (10, 22).

Thus, the null hypothesis is failed to reject.

There is not enough evidence to warrant rejection of the claim that the sequence of digits (odd and even) is random.

Thus, the sequence of the first digits is random.

Since the sequence of digits occurs randomly, it can be said that the lottery is fair and is working as it should.

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Most popular questions from this chapter

Finding Critical Values An alternative to using Table A–9 to find critical values for rank correlation is to compute them using this approximation:

\({r_s} = \pm \sqrt {\frac{{{t^2}}}{{{t^2} + n - 2}}} \)

Here, t is the critical t value from Table A-3 corresponding to the desired significance level and n - 2 degrees of freedom. Use this approximation to find critical values of\({r_s}\)for Exercise 15 “Blood Pressure.” How do the resulting critical values compare to the critical values that would be found by using Formula 13-1 on page 633?

Using the Kruskal-Wallis Test. In Exercises 5–8, use the Kruskal-Wallis test.

Arsenic in Rice Listed below are amounts of arsenic in samples of brown rice from three different states. The amounts are in micrograms of arsenic and all samples have the same serving size. The data are from the Food and Drug Administration. Use a 0.01 significance level to test the claim that the three samples are from populations with the same median.

Arkansas

4.8

4.9

5

5.4

5.4

5.4

5.6

5.6

5.6

5.9

6

6.1

California

1.5

3.7

4

4.5

4.9

5.1

5.3

5.4

5.4

5.5

5.6

5.6

Texas

5.6

5.8

6.6

6.9

6.9

6.9

7.1

7.3

7.5

7.6

7.7

7.7

Using the Wilcoxon Signed-Ranks Test. In Exercises 5–8, refer to the sample data for the given exercises in Section 13-2 on page 611. Use the Wilcoxon signed-ranks test to test the claim that the matched pairs have differences that come from a population with a median equal to zero. Use a 0.05 significance level.

Exercise 6 “Speed Dating: Attractiveness”

Speed Dating Listed on the top of the next page are attribute ratings of males by females who participated in speed dating events (from Data Set 18 “Speed Dating” in Appendix B ). In using the Kruskal-Wallis test, we must rank all of the data combined, and then we must find the sum of the ranks for each sample. Find the sum of the ranks for each of the three samples.

Age 20-22

38

42

30

39

47

43

33

31

32

28

Age 23-26

39

31

36

35

41

45

36

23

36

20

Age 27-29

36

42

35.5

27

37

34

22

47

36

32

CPI and the Subway Use CPI/subway data from the preceding exercise to test for a correlation between the CPI (Consumer Price Index) and the subway fare.

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