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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)?

Short Answer

Expert verified

The chi-square distribution is used to test the given claim.

Step by step solution

01

Given information

A contingency table is constructed that shows the number of passengers who survived/died according to whether they were male, female, boy or girl.

02

Distribution of the test statistic

It is required to test the claim that the survival of the passenger is independent of whether the person is a man, woman, boy or girl.

Thus, it is a test of the independence of attributes that involves nominal variables or variables that consist of categories.

Here, the row variable consists of labels “survived” and “died” and the column variable consists of labels “men”, “women”, “boys” and “girls”.

Such types of tests that involve categorical variables are carried out using the chi-square distribution.

Moreover, the other hypotheses tests involving normal distribution, t-distribution and F-distribution are applied only when the variables are quantitative and not qualitative.

Uniform distribution is not used to conduct hypothesis tests.

Therefore, the distribution of the test statistic to test the given claim is the chi-square distribution.

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Most popular questions from this chapter

Cybersecurity The table below lists leading digits of 317 inter-arrival Internet traffic times for a computer, along with the frequencies of leading digits expected with Benford’s law (from Table 11-1 in the Chapter Problem).

a. Identify the notation used for observed and expected values.

b. Identify the observed and expected values for the leading digit of 2.

c. Use the results from part (b) to find the contribution to theχ2test statistic from the category representing the leading digit of 2.

Leading Digit

1

2

3

4

5

6

7

8

9

Benford’s

Law

30.1%

17.6%

12.5%

9.7%

7.9%

6.7%

5.8%

5.1%

4.6%

Leading Digits

of Inter-Arrival

Traffic Times

76

62

29

33

19

27

28

21

22

The table below shows results since 2006 of challenged referee calls in the U.S. Open. Use a 0.05 significance level to test the claim that the gender of the tennis player is independent of whether the call is overturned. Do players of either gender appear to be better at challenging calls?

Was the Challenge to the Call Successful?


Yes

No

Men

161

376

Women

68

152

The accompanying table is from a study conducted

with the stated objective of addressing cell phone safety by understanding why we use a particular ear for cell phone use. (See “Hemispheric Dominance and Cell Phone Use,” by Seidman, Siegel, Shah, and Bowyer, JAMA Otolaryngology—Head & Neck Surgery,Vol. 139, No. 5.)

The goal was to determine whether the ear choice is associated with auditory or language brain hemispheric dominance. Assume that we want to test the claim that handedness and cell phone ear preference are independent of each other.

a. Use the data in the table to find the expected value for the cell that has an observed frequency of 3. Round the result to three decimal places.

b. What does the expected value indicate about the requirements for the hypothesis test?

Right Ear

Left Ear

No Preference

Right-Handed

436

166

40

Left-Handed

16

50

3

Using Yates’s Correction for Continuity The chi-square distribution is continuous, whereas the test statistic used in this section is discrete. Some statisticians use Yates’s correction for continuity in cells with an expected frequency of less than 10 or in all cells of a contingency table with two rows and two columns. With Yates’s correction, we replace

(OE)2Ewith (|OE|0.5)2E

Given the contingency table in Exercise 9 “Four Quarters the Same as $1?” find the value of the test χ2statistic using Yates’s correction in all cells. What effect does Yates’s correction have?

In a clinical trial of the effectiveness of echinacea for preventing

colds, the results in the table below were obtained (based on data from “An Evaluation of Echinacea Angustifoliain Experimental Rhinovirus Infections,” by Turner et al., NewEngland Journal of Medicine,Vol. 353, No. 4). Use a 0.05 significance level to test the claim that getting a cold is independent of the treatment group. What do the results suggest about the

effectiveness of echinacea as a prevention against colds?

Treatment Group


Placebo

Echinacea:

20% Extract

Echinacea:

60% Extract

Got a Cold

88

48

42

Did Not Get a Cold

15

4

10

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