Question 1

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

Given the difference in standard deviations between the two groups, the separate-variance t test (also known as Welch's t test) is the most appropriate. This test does not assume equal variances between the two groups, making it suitable for this scenario.

Question 2

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 brand.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

Since we are interested in testing the proportion of households with favorable views, a Z test for proportion is the most appropriate. The sample size (n=300) is large enough to assume normality due to the central limit theorem. Also, since we don't have information on the population variance, we cannot use a t-test for the mean. Pooled-variance t test and separate-variance t test are also not applicable in this case as we are not comparing means of two populations. Since we want to test the proportion of households in favor of the brand, the most appropriate test would be the Z test for the proportion. This test allows us to determine if the proportion of households with a favorable view is statistically significant and greater than the threshold of 5,000 out of 20,000 households.

Question 3

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 experiment includes four independent groups (software packages 1, 2, 3, and 4), and the objective is to compare the means of each group on the same variable (number of passengers bumped). Therefore, the most appropriate test to use is a one-way ANOVA F test for differences among more than two means. The fact that the variances are roughly the same for the four packages does not affect this choice. The paired t test is used for comparing means within the same group, the pooled-variance t test is used for comparing means of two groups, and the two-way ANOVA F test is used when there is an interaction between two independent variables.

Question 4

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

We are interested in learning about the proportion of fuses that are defective, which is a proportion parameter. Therefore, we should construct a confidence interval estimate for the proportion using the standard normal distribution.

Question 5

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

Question 6

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 best test in this scenario would be a paired t test, as it is comparing two sets of data that are related (i.e. prices for identical materials from two different suppliers). A pooled-variance t test would be appropriate if the samples were independent and had equal variances. The Wilcoxon rank sum test and Kruskal-Wallis rank Test are non-parametric tests that do not assume normality, but they are not appropriate for comparing two sets of paired data.

Question 7

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

Given the non-normal distribution of the data for some packages, the Kruskal-Wallis rank test, which does not assume normal distribution, is the most appropriate choice for comparing the means across the four packages.

Question 8

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 the most appropriate choice for comparing the variability (i.e., the differences in variances) of sales-to-appraisal ratios across the four neighborhoods. It is specifically designed to test the equality of variances across groups.

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.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

The most appropriate test to investigate if primary specialty and origin of medical school degree interact to affect the charges is a two-way ANOVA with interaction effect. This is because we are interested in investigating how two factors (specialty and origin of medical school degree) interact to influence charges, and the two-way ANOVA with interaction effect allows us to test for this interaction. The Tukey-Kramer multiple comparisons procedure for one-way ANOVA and the one-way ANOVA F test for differences among more than two means are appropriate for examining differences between means of a single factor. The one-way ANOVA F test for interaction effect only examines differences between the means of one factor at different levels of the other factor, but we want to investigate the interaction between the two factors.

Question 10

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)  test for difference in proportions.
D)Kruskal-Wallis rank Test.

Accepted Answer

We need to determine if the proportion of defects is significantly different between the two groups. Therefore, we will use a Z test for the difference in proportions. A paired t test is used when there are paired observations, which is not the case here. The 11ebc114_12dd_94a4_8acb_8b894f8e8363_TB8562_11 test is used when comparing more than two groups. Kruskal-Wallis rank test is used when the data is not normally distributed. The best test to compare the proportion of defects between two groups with a sample size greater than 30 is the Z test for difference in proportions. The paired t-test is used when comparing two related samples, which is not the case here. The 11ebc114_12dd_94a4_8acb_8b894f8e8363_TB8562_11 test is used for comparing proportions of more than two groups. The Kruskal-Wallis rank test is used for comparing medians of more than two groups.

Question 11

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

Since we are comparing the proportions of two groups, the appropriate test to use is the z-test for difference in proportions. This test allows us to determine if there is a significant difference in the proportion of men and women who believe that sexual discrimination is a problem. The pooled-variance t-test would be inappropriate since the variance of the two groups may not be equal. The paired t-test would be inappropriate since the two groups are independent. The Wilcoxon rank sum test would be inappropriate since it is used for nonparametric data.

Question 12

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

The most appropriate test in this case would be a pooled-variance t test, which compares the means of two independent groups assuming that the two populations have equal variances. This test would allow us to determine if there is a significant difference between the mean starting salaries of males and females in the MBA program. Both groups are normally distributed and have almost the same variability, making the assumptions of the pooled-variance t test appropriate. The separate-variance t test would not be appropriate as it assumes the variances of the two groups are different, which is not suggested by the sample standard deviations. The paired t test would not be appropriate as it is used to compare the means of two related groups, which is not the case here. Finally, the Wilcoxon rank sum test is a nonparametric test used when the data is not normally distributed, but since the data are assumed to be normally distributed in this case, the Wilcoxon rank sum test would not be the most appropriate choice.

Question 13

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

A t-test for the mean is the most appropriate because the sample size is less than 30, and the population standard deviation is unknown, requiring the use of sample data to estimate the mean revenue.

Question 14

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 15

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 Z test for difference in proportions is the appropriate test to determine if there is a significant difference in preference between the different gender groups. This test is used when the sample size is large and there are two independent populations being compared based on their proportions. In this case, we are comparing the proportion of men who prefer Pepsi to the proportion of women who prefer Pepsi.

Question 16

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 appropriate for comparing the means of two related samples, in this case, the before and after scores of the same 8 students. Since the exam scores are assumed to be normally distributed, the paired t test can be used to test whether there is a statistically significant difference between the two sets of scores. The pooled-variance t test is appropriate for comparing the means of two independent samples with equal variances. The Wilcoxon rank sum test and the Kruskal-Wallis rank test are nonparametric tests that are used when the assumptions of normality and equal variances are not met. However, since the question explicitly states that the exam scores are normally distributed, it is appropriate to use the paired t test.

Question 17

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

Since the data is not normally distributed for either group, a non-parametric test should be used. The Wilcoxon rank sum test, also called the Mann-Whitney U test, is appropriate for comparing two independent groups of non-normally distributed data with equal variances.

Question 18

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

Since the survey claims a proportion of doctors recommending aspirin, we need to use a test for proportions. The sample size is large enough (n=100) to use a Z test. Therefore, we need to perform a Z test for the proportion.

Question 19

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 decide?
A)t test for the mean.
B)Z test for the proportion.
C)Pooled-variance t test.
D)Separate-variance t test.

Accepted Answer

This is the appropriate test to use when trying to determine if a sample mean is significantly different from a population mean, or a hypothesized value. In this case, the owner wants to compare the mean age of her customers to the hypothesized value of 30. The t test for the mean is also appropriate because the sample size is large enough (n=250) to assume normality, and the population standard deviation is unknown. The other options, such as the Z test for proportions, pooled-variance t test, and separate-variance t test, are not appropriate in this scenario.

Question 20

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...

Quiz 18: A Roadmap for Analyzing Data

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?

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?