Question 1

A physician and president of a Tampa Health Maintenance Organization (HMO) are attempting to show the benefits of managed health care to an insurance company. The physician believes that
Certain types of doctors are more cost-effective than others. To investigate this, the president
Obtained independent random samples of 20 HMO physicians from each of 4 primary specialties -
General Practice (GP), Internal Medicine (IM), Pediatrics (PED), and Family Physicians (FP) -
And recorded the total charges per member per month for each. A second variable which the
President believes influences total charges per member per month is whether the doctor is a
Foreign or USA medical school graduate. To investigate this, the president also collected data on
20 foreign medical school graduates in each of the 4 primary specialty types described above. So
Information on charges for 40 doctors (20 foreign and 20 USA medical school graduates) was
Obtained for each of the 4 specialties. The president has already found out that specialty types
And origin of the medical degree do not interact to affect the charges. Which of the following
Tests will be the most appropriate to find out if the primary specialty affects the charges?
A) Tukey-Kramer multiple comparisons procedure for one-way ANOVA.
B) One-way ANOVA F test for differences among more than two means.
C) Two-way ANOVA F test for primary specialty effect.
D) Two-way ANOVA F test for origin of the medical degree effect.

Accepted Answer

The two-way ANOVA F test for primary specialty effect is appropriate because it allows for the examination of the effect of primary specialty on charges while accounting for the other factor (origin of the medical degree) without interaction.

Question 2

A physician and president of a Tampa Health Maintenance Organization (HMO) are attempting to show the benefits of managed health care to an insurance company. The physician believes that
Certain types of doctors are more cost-effective than others. To investigate this, the president
Obtained independent random samples of 20 HMO physicians from each of 4 primary specialties -
General Practice (GP), Internal Medicine (IM), Pediatrics (PED), and Family Physicians (FP) -
And recorded the total charges per member per month for each. A second variable which the
President believes influences total charges per member per month is whether the doctor is a
Foreign or USA medical school graduate. To investigate this, the president also collected data on
20 foreign medical school graduates in each of the 4 primary specialty types described above. So
Information on charges for 40 doctors (20 foreign and 20 USA medical school graduates) was
Obtained for each of the 4 specialties. Which of the following tests will be the most appropriate
To find out if the primary specialty and the origin of medical school degree interact to affect the
Charges?
A) Tukey-Kramer multiple comparisons procedure for one-way ANOVA.
B) One-way ANOVA F test for differences among more than two means.
C) One-way ANOVA F test for interaction effect.
D) Two-way ANOVA F test for interaction effect.

Accepted Answer

A two-way ANOVA F test is appropriate here as it allows for the examination of the interaction effect between two independent variables (primary specialty and origin of medical school degree) on a dependent variable (charges).

Question 3

A powerful women's group has claimed that men and women differ in attitudes about sexual discrimination. A group of 50 men (group 1) and 40 women (group 2) were asked if they thought
Sexual discrimination is a problem in the United States. Of those sampled, 11 of the men and 19
Of the women did believe that sexual discrimination is a problem. Which of the following tests
Will you use to find out if there is any difference in attitudes about sexual discrimination?
A) Pooled-variance t test.
B) Paired t test.
C) Z test for difference in proportions.
D) Wilcoxon rank sum test.

Accepted Answer

The Z test for difference in proportions is used to compare the proportions of two independent groups. In this case, we are comparing the proportion of men who believe that sexual discrimination is a problem to the proportion of women who believe that sexual discrimination is a problem.

Question 4

A quality control engineer is in charge of the manufacture of computer disks. Two different processes can be used to manufacture the disks. He suspects that the Kohler method produces a
Greater proportion of defects than the Russell method. He samples 150 of the Kohler and 200 of
The Russell disks and finds that 27 and 18 of them, respectively, are defective. If Kohler is
Designated as "Group 1" and Russell is designated as "Group 2," which of the following tests will
You use to find out if the Kohler method is worse than the Russell method?
A) Paired t test.
B) Z test for difference in proportions.
C) $\chi ^ { 2 }$ test for difference in proportions.
D) Kruskal-Wallis rank Test.

Accepted Answer

The Z test for difference in proportions is appropriate here because it compares the proportions of defects between two independent groups (Kohler and Russell methods) to determine if there is a statistically significant difference.

Question 5

A survey claims that 9 out of 10 doctors recommend aspirin for their patients with headaches. To test this claim, a random sample of 100 doctors results in 83 who indicate that they recommend
Aspirin. Which of the following tests will you perform?
A) t test for the mean.
B) Z test for the proportion.
C) Pooled-variance t test.
D) Separate-variance t test.

Accepted Answer

The Z test for the proportion is appropriate here because we are dealing with a sample proportion (83 out of 100) and comparing it to a claimed population proportion (9 out of 10 or 0.9).

Question 6

A few years ago, Pepsi invited consumers to take the "Pepsi Challenge." Consumers were asked to decide which of two sodas, Coke or Pepsi, they preferred in a blind taste test. Pepsi was
Interesting in determining what factors played a role in people's taste preferences. One of the
Factors studied was the gender of the consumer. Data on the percentage of men and women
Depicting preference for Pepsi were collected. Which of the following tests will you use to find
Out if there is any difference in preference between the different gender groups?
A) Kruskal-Wallis rank Test.
B) Paired t test.
C) Z test for difference in proportions.
D) Wilcoxon rank sum test.

Accepted Answer

The data is categorical and the groups are independent, so the appropriate test is the z test for difference in proportions.

Question 7

A buyer for a manufacturing plant suspects that his primary supplier of raw materials is overcharging. In order to determine if his suspicion is correct, he contacts a second supplier and
Asks for the prices on various identical materials. He wants to compare these prices with those of
His primary supplier. He collected data on 6 different materials from both suppliers. He believes
That the differences are normally distributed. Which of the following tests will be the most
Appropriate?
A) Pooled-variance t test.
B) Paired t test.
C) Wilcoxon rank sum test.
D) Kruskal-Wallis rank Test.

Accepted Answer

The paired t test is appropriate here because the buyer is comparing two sets of related data (prices from two suppliers for the same materials).

Question 8

An airline wants to select a computer software package for its reservation system. Four software packages (1, 2, 3, and 4) are commercially available. An experiment is set up in which each
Package is used to make reservations for 5 randomly selected weeks and data on the number of
Passengers that are bumped over a month are collected. (A total of 20 weeks was included in the
Experiment.) The variance on the number of passengers that are bumped is found to be roughly
The same for the 4 packages. Which of the following tests will be the most appropriate to find out
If the mean number of passengers being bumped over a month is the same across the 4 packages?
A) Paired t test.
B) Pooled-variance t test.
C) One-way ANOVA F test for differences among more than two means.
D) Two-way ANOVA F test for interaction effect.

Accepted Answer

The one-way ANOVA F test is appropriate for comparing the means of more than two groups, which is the case here with four software packages.

Question 9

A physician and president of a Tampa Health Maintenance Organization (HMO) are attempting to show the benefits of managed health care to an insurance company. The physician believes that
Certain types of doctors are more cost-effective than others. To investigate this, the president
Obtained independent random samples of 20 HMO physicians from each of 4 primary specialties -
General Practice (GP), Internal Medicine (IM), Pediatrics (PED), and Family Physicians (FP) -
And recorded the total charges per member per month for each. A second variable which the
President believes influences total charges per member per month is whether the doctor is a
Foreign or USA medical school graduate. To investigate this, the president also collected data on
20 foreign medical school graduates in each of the 4 primary specialty types described above. So
Information on charges for 40 doctors (20 foreign and 20 USA medical school graduates) was
Obtained for each of the 4 specialties. The president has already found out that specialty types
And origin of the medical degree do not interact to affect the charges. He has also found out
Special types do have an impact on average charges. Which of the following tests will be the
Most appropriate to find out which primary specialty has the highest charges?
A) Tukey-Kramer multiple comparisons procedure for one-way ANOVA.
B) Tukey multiple comparisons procedure for two-way ANOVA.
C) Two-way ANOVA F test for primary specialty effect.
D) Two-way ANOVA F test for origin of the medical degree effect.

Accepted Answer

The answer of A physician and president of a Tampa...

Question 10

A sample of 100 fuses from a very large shipment is found to have 10 that are defective. Based on this information, which of the following will you construct to learn about the proportion of
Fuses that are defective?
A) Confidence interval estimate for the total using the Student's t distribution.
B) Confidence interval estimate for the mean using the Student's t distribution.
C) Confidence interval estimate for the proportion using the standard normal distribution.
D) Confidence interval estimate for the difference between two means using the standard normal distribution.

Accepted Answer

A confidence interval estimate for the proportion using the standard normal distribution is appropriate when estimating the proportion of defective fuses in a large shipment based on a sample.

Question 11

A realtor wants to compare the variability of sales-to-appraisal ratios of residential properties sold in four neighborhoods (A, B, C, and D). Four properties are randomly selected from each
Neighborhood and the ratios recorded for each were collected. Which of the following tests will
Be the most appropriate?
A) Kruskal-Wallis rank Test.
B) Tukey-Kramer multiple comparisons procedure for one-way ANOVA.
C) Levene's test.
D) Wilcoxon rank sum test.

Accepted Answer

Levene's test is used to assess the equality of variances (homogeneity of variance) across different groups, which is what the realtor wants to compare.

Question 12

A pizza chain is considering opening a new store in an area that currently does not have any such stores. The chain will open if there is evidence that more than 5,000 of the 20,000 households in
The area have a favorable view of its brain. It conducts a telephone poll of 300 randomly selected
Households in the area and finds that 96 have a favorable view. Which of the following tests will
Be the most appropriate?
A) t test for the mean.
B) Z test for the proportion.
C) Pooled-variance t test.
D) Separate-variance t test.

Accepted Answer

A Z test for the proportion is appropriate here because the problem involves testing a hypothesis about a population proportion (households with a favorable view) based on a sample proportion.

Question 13

An airline wants to select a computer software package for its reservation system. Four software packages (1, 2, 3, and 4) are commercially available. An experiment is set up in which each
Package is used to make reservations for 5 randomly selected weeks and data on the number of
Passengers that are bumped over a month are collected. (A total of 20 weeks was included in the
Experiment.) The variability of the number of passengers that are bumped is found to be roughly
The same for the 4 packages. The distribution on the number of passengers that are bumped has
Been found out to be right-skewed for package 1 and 4, left-skewed for package 2 and normal for
Package 3. Which of the following tests will be the most appropriate to find out if the mean
Number of passengers being bumped over a month is the same across the 4 packages?
A) Paired t test.
B) Pooled-variance t test.
C) One-way ANOVA F test for differences among more than two means.
D) Kruskal-Wallis rank test.

Accepted Answer

The answer of An airline wants to select a computer...

Question 14

An airline wants to select a computer software package for its reservation system. Four software packages (1, 2, 3, and 4) are commercially available. The airline will choose the package that
Bumps as few passengers, on the average, as possible during a month. An experiment is set up in
Which each package is used to make reservations for 5 randomly selected weeks. (A total of 20
Weeks was included in the experiment.) Which of the following tests will be the most
Appropriate?
A) Paired t test.
B) Wilcoxon rank sum test.
C) Kruskal-Wallis rank Test.
D) Tukey-Kramer multiple comparisons procedure for one-way ANOVA.

Accepted Answer

The answer of An airline wants to select a computer...

Question 15

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. They will choose to use the
Preservative that can keep the meat fresh for the longest amount of time. Suppose 15 cuts of
Fresh meat are treated with preservative I and 15 are treated with preservative II, and the number
Of hours until spoilage begins is recorded for each of the 30 cuts of meat. Suppose the variability
Of the number of hours until spoilage is the same for meat treated by both preservatives but the
Normal probability plots reveal that the number of hours until spoilage is right-skewed for the 15
Cuts treated by preservative I and left-skewed for the 15 cuts treated with preservative II. Which
Of the following tests will be the most appropriate?
A) Pooled-variance t test.
B) Paired t test.
C) Wilcoxon rank sum test.
D) Levene's test.

Accepted Answer

The Wilcoxon rank sum test is appropriate for comparing two independent samples when the data is not normally distributed, as is the case here with skewed distributions.

Question 16

The owner of a local nightclub has recently surveyed a random sample of n = 250 customers of the club. She would now like to determine whether or not the mean age of her customers is more
Than 30. If so, she plans to alter the entertainment to appeal to an older crowd. If not, no
Entertainment changes will be made. Which of the following tests will you perform to help her
Make a decision?
A) t test for the mean.
B) Z test for the proportion.
C) Pooled-variance t test.
D) Separate-variance t test.

Accepted Answer

A t test for the mean is appropriate here because the owner wants to determine if the mean age of customers is greater than 30, which involves comparing a sample mean to a known value.

Question 17

To test the effectiveness of a business school preparation course, 8 students took a general business test before and after the course. Suppose the before and after exam scores are both
Normally distributed. Which of the following tests will be the most appropriate?
A) Pooled-variance t test.
B) Paired t test.
C) Wilcoxon rank sum test.
D) Kruskal-Wallis rank Test.

Accepted Answer

The paired t-test is the most appropriate test because it is used to compare the means of two related samples, which is the case here. The before and after exam scores are from the same students, so they are related.

Question 18

Are Japanese managers more motivated than American managers? A randomly selected group of 100 managers from each group were administered the Sarnoff Survey of Attitudes Toward Life
(SSATL), which measures motivation for upward mobility. The mean and standard deviation of
The SSATL scores are computed. The standard deviations of the SSATL scores suggest that the
Standard deviation from the two groups is very different. Which of the following tests will be the
Most appropriate?
A) t test for the mean.
B) Z test for the proportion.
C) Pooled-variance t test.
D) Separate-variance t test.

Accepted Answer

Since the standard deviations of the SSATL scores from the two groups are different, the most appropriate test to use is the separate-variance t test. This test does not assume equal variances in the two groups and is therefore more appropriate than the pooled-variance t test. The Z test for proportions would be appropriate if the outcome of interest was a categorical variable, but SSATL scores are continuous. The t test for the mean assumes that variances are equal, which is not the case here. Therefore, the best choice is a separate-variance t test.

Question 19

An entrepreneur is considering the purchase of a coin-operated laundry. The current owner claims that over the past 5 years, the mean daily revenue was $675 with a standard deviation of $75. A
Sample of 30 days reveals a daily mean revenue of $625 and a standard deviation of $70. Which
Of the following tests will be the most appropriate?
A) t test for the mean.
B) Z test for the proportion.
C) Pooled-variance t test.
D) Separate-variance t test.

Accepted Answer

The t test for the mean is the most appropriate test because it is used to compare the mean of a sample to a known population mean. In this case, the population mean is $675 and the sample mean is $625.

Question 20

A researcher randomly sampled 30 graduates, 18 males and 12 females, of an MBA program and recorded data concerning their starting salaries. Of primary interest to the researcher was the
Effect of gender on starting salaries. Statistics of the mean salaries of the females and males in the
Sample were computed. The sample standard deviations suggest that the variability of starting
Salaries of the two groups is almost the same. Suppose the starting salaries from both groups can
Be considered as normally distributed. Which of the following tests will be the most appropriate?
A) Pooled-variance t test.
B) Separate-variance t test.
C) Paired t test.
D) Wilcoxon rank sum test.

Accepted Answer

Since the sample standard deviations suggest that the variability of starting salaries of the two groups is almost the same and the data is normally distributed, a pooled-variance t test is appropriate for comparing the means of two independent samples with equal variances.

Quiz 17: Getting Ready to Analyze Data

A survey claims that 9 out of 10 doctors recommend aspirin for their patients with headaches. To test this claim, a random sample of 100 doctors results in 83 who indicate that they recommend Aspirin. Which of the following tests will you perform?

A sample of 100 fuses from a very large shipment is found to have 10 that are defective. Based on this information, which of the following will you construct to learn about the proportion of Fuses that are defective?

To test the effectiveness of a business school preparation course, 8 students took a general business test before and after the course. Suppose the before and after exam scores are both Normally distributed. Which of the following tests will be the most appropriate?