Question 1

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?

Accepted Answer

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

Question 2

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?

Accepted Answer

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

Question 3

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?

Accepted Answer

Given that the study involves two factors (primary specialty and origin of the medical degree) without interaction, a two-way ANOVA is appropriate to assess the effect of each factor separately. Since the question specifically asks about the effect of primary specialty on charges, a two-way ANOVA F test for primary specialty effect is the most suitable choice.

Question 4

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 Copyright ©2019 Pearson Education,Inc.
18-18 A Roadmap for Analyzing Data
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?

Accepted Answer

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

Question 5

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?

Accepted Answer

The appropriate test to compare proportions between two independent groups is the Z test for difference in proportions. Therefore, choice C is the best option. The pooled-variance t test is used to compare means between two independent groups, which is not applicable in this case. The paired t test is used when the same individuals are measured twice or two individuals are matched on some variable, which is not the case here. The Wilcoxon rank sum test is a nonparametric test that is used to compare the medians of two independent groups, but since we are interested in comparing proportions, it is not the best option.

Question 6

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?

Accepted Answer

Pooled-variance t test is appropriate when the sample standard deviations are approximately equal and the distribution is normal. In this case, the standard deviations of the two groups are almost the same and it is stated that the starting salaries can be considered as normally distributed. Therefore, a pooled-variance t test is the most appropriate choice.

Question 7

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?

Accepted Answer

We need to test whether the mean age of the customers is more than 30 or not. Hence, we need to perform a hypothesis test for the population mean. Since the sample size is large (n=250), we can use the t test for the mean.

Question 8

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?

Accepted Answer

The most appropriate test for comparing the prices of identical materials from two suppliers, assuming the differences are normally distributed and the data is paired (each material's price from one supplier is directly compared to its price from the other supplier), is the Paired t test. This test is specifically designed for comparing the means of two related groups to determine if there is a statistically significant difference between them.

Question 9

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?

Accepted Answer

A t-test for the mean is most appropriate because the sample size is small (n < 30) and the population standard deviation is unknown, requiring the use of the sample standard deviation.

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?

Accepted Answer

We will use a Z test for difference in proportions to compare the two manufacturing methods because we are comparing two independent groups with a dichotomous outcome (defective or not defective). A paired t test would be used if the same group was measured twice (before and after a treatment or with two different methods). The Kruskal-Wallis rank test is used to compare three or more groups with nonparametric data. The chi-square test for difference in proportions is used for categorical data with more than two groups.

Question 11

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?

Accepted Answer

The normal probability plots reveal that the number of hours until spoilage is not normally distributed for either group. Therefore, a Wilcoxon rank sum test should be used instead of a t test. The fact that there is equal variability between the two groups suggests that a pooled-variance t test is not necessary. A paired t test is not appropriate because the two preservatives are being compared independently on different cuts of meat. Levene's test is used to test for equal variances, which is not the issue in this scenario.

Question 12

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?

Accepted Answer

We will perform a Z test for the proportion since we are testing a claim about a proportion (9 out of 10 doctors) using a sample proportion (83 out of 100 doctors). The sample size is large enough (n=100) to justify using a Z test instead of a t test.

Question 13

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?

Accepted Answer

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

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.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?

Accepted Answer

One-way ANOVA F test for differences among more than two means is the most appropriate test in this situation because it can compare the means of more than two groups (in this case, 4 software packages) to determine if there is a statistically significant difference in the number of passengers being bumped. Additionally, the fact that the variance is roughly the same for all 4 packages suggests that the assumption of equal variances required for the ANOVA test is satisfied. The paired t-test is used when the same set of subjects is measured under two different conditions, which is not the case here. The pooled-variance t-test is only appropriate when comparing two groups, not multiple groups. The two-way ANOVA F test would be appropriate if there were two independent variables being tested, but there is only one independent variable (the software package).

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?

Accepted Answer

Since we are comparing the percentages of men and women who prefer Pepsi, we need to use a test for the difference in proportions. The Z test for difference in proportions is appropriate when we have two independent groups (in this case, men and women) and we want to compare their proportions on a categorical variable (in this case, preference for Pepsi). The other three tests listed are not appropriate for this type of data.

Question 16

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?

Accepted Answer

In this scenario, we are interested in estimating the proportion of defective fuses in the entire shipment. As we only have one sample, and the variable of interest is binary (defective or not defective), the appropriate method to use is a confidence interval estimate for the proportion using the standard normal distribution. The other choices are not relevant in this scenario.

Question 17

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?

Accepted Answer

Levene's test is the most appropriate choice for comparing the variability (as opposed to the means) of sales-to-appraisal ratios across multiple groups. It specifically tests for equality of variances across groups.

Question 18

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?

Accepted Answer

Since the question is about the proportion of households in the area with a favorable view of the pizza chain, a z test for the proportion would be most appropriate.

Question 19

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?

Accepted Answer

A two-way ANOVA is appropriate when there are two factors (in this case, primary specialty and origin of medical school degree) that may interact to affect the dependent variable (charges per member per month). The objective is to determine if there is a significant interaction effect between the two factors on the dependent variable.

Question 20

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?

Accepted Answer

The paired t-test is appropriate when comparing the same group of individuals before and after an intervention, such as the business school preparation course in this case. The other tests listed are not appropriate for this type of analysis. The pooled-variance t-test is typically used when comparing two independent groups, the Wilcoxon rank sum test is a non-parametric test that compares two independent groups, and the Kruskal-Wallis rank test is used for comparing three or more independent groups.

Quiz 18: A Roadmap for Analyzing 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?