Statistics 4

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Question 1

TABLE 11-3. A computer used by a 24-hour banking service is supposed to randomly assign each transaction to one of 5 memory locations. A check at the end of a day's transactions gave the counts shown in the table to each of the 5 memory locations, along with the number of reported errors.

Referring to Table 11-3, which test would be used to properly analyze the data in this experiment?

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Question 1 answers

chi-square test of independence

chi-square test for differences between two proportions (independent samples)

chi-square test for differences between two proportions (related samples)

chi-square test for differences among more than two proportions

Question 2

As the number of degrees of freedom increases, the chi-square distribution becomes

Question 2 answers

progressively more symmetrical

progressively more right-skewed

progressively more left-skewed

The shape is not affected by the degrees of freedom.

Question 3

If we use the chi-square method of analysis to test for the difference between proportions, we must assume that there are at least 5 observed frequencies in each cell of the contingency table.

Question 3 answers

True

False

Question 4

TABLE 11-4. One criterion used to evaluate employees in the assembly section of a large factory is the number of defective pieces per 1,000 parts produced. The quality control department wants to find out whether there is a relationship between years of experience and defect rate. Since the job is repetitious, after the initial training period any improvement due to a learning effect might be offset by a loss of motivation. A defect rate is calculated for each worker in a yearly evaluation. The results for 100 workers are given in the table below.

Referring to Table 11-4, what is the expected number of employees with 1 to 4 years of training time and a high defect rate?

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Question 4 answers

12.00

8.64

6.67

6.00

Question 5

In testing the difference between two proportions using the normal distribution, we may use either a one-tailed Chi-square test or two-tailed Z test.

Question 5 answers

True

False

Question 6

The chi-squared distribution is:

Question 6 answers

right-skewed

left-skewed

symmetric

binomial

Question 7

TABLE 11-1. A study published in the American Journal of Public Health was conducted to determine whether the use of seat belts in motor vehicles depends on ethnic status in San Diego County. A sample of 792 children treated for injuries sustained from motor vehicle accidents was obtained, and each child was classified according to (1) ethnic status (Hispanic or non-Hispanic) and (2) seat belt usage (worn or not worn) during the accident.

Referring to Table 11-1, at 5% level of significance, the critical value of the test statistic is

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Question 7 answers

3.8415

5.9914

9.4877

13.2767

Question 8

The Marascuilo procedures is an example of a _____ test.

Question 8 answers

a priori

ad hoc

post hoc

post mortem

Question 9

TABLE 11-2. Many companies use well-known celebrities as spokespersons in their TV advertisements. A study was conducted to determine whether brand awareness of female TV viewers and the gender of the spokesperson are independent. Each in a sample of 300 female TV viewers was asked to identify a product advertised by a celebrity spokesperson. The gender of the spokesperson and whether or not the viewer could identify the product was recorded.

Referring to Table 11-2, the degrees of freedom of the test statistic are

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Question 9 answers

299

Question 10

Referring to Table 11-4, which test would be used to properly analyze the data in this experiment to determine whether there is a relationship between defect rate and years of experience?

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Question 10 answers

X^2 test for independence

X^2 test for differences between two proportions (independent samples)

X^2 test for differences between two proportions (related samples)

X^2 test for differences among more than two proportions

Question 11

Referring to Table 11-4, of the cell for 1 to 4 years of training time and a high defect rate, what is the contribution to the overall ÷2 statistic for the independence test?

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Question 11 answers

0.36

0.1296

0.015

0.0144

Question 12

Referring to Table 11-3, the degrees of freedom of the test statistic is

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Question 12 answers

448

Question 13

TABLE 10-3. The use of preservatives by food processors has become a controversial issue. Suppose 2 preservatives are extensively tested and determined safe for use in meats. A processor wants to compare the preservatives for their effects on retarding spoilage. Suppose 15 cuts of fresh meat are treated with preservative A and 15 are treated with preservative B, and the number of hours until spoilage begins is recorded for each of the 30 cuts of meat. Referring to Table 10-3, state the test statistic for determining if the population variances differ for preservatives A and B.

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Question 13 answers

F = - 3.10

F = 0.5908

F = 0.7687

F = 0.8250

Question 14

TABLE 10-5. To test the effectiveness of a business school preparation course, 8 students took a general business test before and after the course. Referring to Table 10-5, what is the critical value for testing at the 5% level of significance whether the business school preparation course is effective in improving exam scores?

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Question 14 answers

2.365

2.145

1.761

1.895

Question 15

Given the following information, calculate sp2, the pooled sample variance that should be used in the pooled-variance t test:

s12 = 4 and n1 = 16

s22 = 6 and n2 = 25

Question 15 answers

sp2 = 6

sp2 = 5

sp2 = 5.23

sp2 = 4

Question 16 text

The t test for the mean difference between two (2) related populations assumes that the

Question 16 answers

population sizes are equal.

sample variances are equal.

population of differences is approximately normal or sample sizes are large enough.

All of the above.

Question 17

Given the following information, calculate the degrees of freedom that should be used in the pooled-variance t test:

s12 = 4 and n1 = 16

s22 = 6 and n2 = 25

Question 17 answers

df = 41

df = 39

df = 16

df = 25

Question 18

In testing for the differences between the means of two (2) independent populations where the variances in each population are unknown but assumed equal, the degrees of freedom are

Question 18 answers

n - 1

n1 + n2 - 1

n1 + n2 - 2

n - 2

Question 19

TABLE 10-2. Referring to Table 10-2, the researcher was attempting to show statistically that the female MBA graduates (Population 1 Sample) have a significantly lower mean starting salary than the male MBA graduates. The proper conclusion for this test is:

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Question 19 answers

At the alpha = 0.10 level, there is sufficient evidence to indicate a difference in the mean starting salaries of male and female MBA graduates.

At the alpha = 0.10 level, there is sufficient evidence to indicate that females have a lower mean starting salary than male MBA graduates.

At the alpha = 0.10 level, there is sufficient evidence to indicate that females have a higher mean starting salary than male MBA graduates.

At the alpha = 0.10 level, there is insufficient evidence to indicate any difference in the mean starting salaries of male and female MBA graduates.

Question 20

TABLE 10-1. Are Japanese managers more motivated than American managers? A randomly selected group of each were administered the Sarnoff Survey of Attitudes Toward Life (SSATL), which measures motivation for upward mobility.

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Referring to TABLE 10-1, judging from the way the data were collected, which test would likely be most appropriate to employ?

Question 20 answers

Paired t test

Pooled-variance t test for the difference between two means

Independent samples Z test for the difference between two means

Related samples Z test for the mean difference

Question 21

In what type of test is the variable of interest the difference between the values of the observations rather than the observations themselves?

Question 21 answers

A test for the equality of variances from two (2) independent populations.

A test for the difference between the means of two (2) related populations.

A test for the difference between the means of two (2) independent populations.

All of the above.

Question 22 text Question 22 4 points Save

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Question 22 answers

0.0860

- 1.4019

- 1.7011

- 6,733.33

Question 23 text Question 23 4 points Save

TABLE 10-4. A real estate company is interested in testing whether, on average, families in Gotham have been living in their current homes for less time than families in Metropolis have. Assume that the two population variances are equal. A random sample of 100 families from Gotham and a random sample of 150 families in Metropolis yield the data on length of residence in current homes. Referring to Table 10-4, what is(are) the critical value(s) of the relevant hypothesis test if the level of significance is 0.05?

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Question 23 answers

t . Z = - 1.645

t . Z = ± 1.96

t . Z = - 1.96

t . Z = - 2.080

Question 24 text Question 24 4 points Save

In testing for differences between the means of two (2) related populations where the variance of the differences is unknown, the degrees of freedom are

Question 24 answers

n - 1

n1 + n2 - 1

n1 + n2 - 2

n - 2

Question 25 text Question 25 4 points Save

TABLE 10-5. To test the effectiveness of a business school preparation course, 8 students took a general business test before and after the course. Referring to Table 10-5, the value of the sample mean difference is _______ if the difference scores reflect the results of the exam after the course minus the results of the exam before the course.

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Question 25 answers

400