Assuming that the population is normally distributed, construct a 95% confidence interval for the population mean, based on the following sample of size n = 7: 1 2 3 4 5 6 20 Change the value of 20 to 7 and recalculate the confidence interval. Using these results, describe the effect of an outlier (i.e., an extreme value) on the confidence interval.
> Under what conditions should you use the F test to examine possible differences in the variances of two independent populations?
> Under what conditions should you use the pooled-variance t test to examine possible differences in the means of two independent populations?
> What are some of the criteria used in the selection of a particular hypothesis-testing procedure?
> The file AirportRating contains the rating of large and medium size airports in the United States and Canada. Source: Data extracted from N. Trejos, “Portland, Indianapolis Top Airport Rankings, USA Today, December 16, 2016, p. 4B. For large and medium a
> A taxicab company has been receiving an increasing number of complaints concerning the delay time between when a call for a taxicab is received and when the passenger is picked up. The file TaxiDelays contains the delay times (in minutes) for two drivers
> We Are Social and Hootsuite reported that the typical American spends 2.02 hours (121 minutes) per day accessing the Internet through a mobile device. Source: Digital in 2017 Global Overview, available at bit.ly/2jXeS3F. You wonder if males and females s
> The annual NFL Super Bowl is the most widely watched sporting event in the United States each year. In recent years, there has been a great deal of interest in the ads that appear during the game. These ads vary in length with most lasting 30 seconds or
> What social media tools do marketers commonly use? A survey by Social Media Examiner of B2B marketers (marketers that focus primarily on attracting businesses) and B2C marketers (marketers that primarily target consumers) reported that 267 (81%) of B2B m
> A bank with a branch located in a commercial district of a city has the business objective of improving the process for serving customers during the noon-to-1 p.m. lunch period. To do so, the waiting time (defined as the number of minutes that elapses fr
> Accounting Today identified top accounting firms in 10 geographic regions across the United States. All 10 regions reported growth in 2016. The Southeast and Gulf Coast regions reported growths of 12.03% and 9.47%, respectively. A characteristic descript
> Is there a difference in the variance of the satisfaction rating of traditional cellphone providers who bill for service at the end of a month (often under a contract) and prepaid cellphone service providers who bill in advance without a contract? The fi
> In Problem 9.40, what is the statistical decision if you test the null hypothesis at the 0.01 level of significance? Problem 9.40: In a one-tail hypothesis test where you reject H0 only in the lower tail, what is the p-value if ZSTAT = +1.38?
> In Problem 10.43, assume that two samples are selected from independent normally distributed populations. a. At the 0.05 level of significance, is there evidence of a difference between σ12 and σ22? b. Suppose that you want to perform a one-tail test. At
> The following information is available for two samples selected from independent but very right-skewed populations: Population A: n1 = 16 S12 = 47.3 Population B: n2 = 13 S22 = 36.4 Should you use the F test to test the null hypothesis of equality of v
> In Problem 10.39, what is your statistical decision? Problem 10.39: The following information is available for two samples selected from independent normally distributed populations: Population A: n1 = 25 S12 = 161.9 Population B: n2 = 25 S22 = 133.7
> In Problems 10.38 and 10.39, what is the upper-tail critical value for F if the level of significance, α, is 0.05 and the alternative hypothesis is H1: σ12 ≠ σ22?
> In Problem 10.39, how many degrees of freedom are there in the numerator and denominator of the F test? Problem 10.39: The following information is available for two samples selected from independent normally distributed populations: Population A: n1 =
> The Society for Human Resource Management (SHRM) collaborated with Globoforce on a series of organizational surveys with the goal of identifying challenges that HR leaders face and what strategies help them conquer those challenges. A 2016 survey indicat
> The U.S. Department of Transportation requires tire manufacturers to provide tire performance information on the sidewall of a tire to better inform prospective customers as they make purchasing decisions. One very important measure of tire performance i
> Does Cable Video on Demand (VOD D4+) increase ad effectiveness? A 2015 VOD study compared general TV and VOD D4+ audiences after viewing a brand ad. Data were collected on whether the viewer indicated that the ad made them want to visit the brand website
> An online survey asked 1,004 adults “If purchasing a used car made certain upgrades or features more affordable, what would be your preferred luxury upgrade?” The results indicated that 9% of the males and 14% of the females answered window tinting. Sour
> Let n1 = 100, X1 = 45, n2 = 50, and X2 = 25. a. At the 0.01 level of significance, is there evidence of a significant difference between the two population proportions? b. Construct a 99% confidence interval estimate for the difference between the two po
> Let n1 = 100, X1 = 50, n2 = 100, and X2 = 30. a. At the 0.05 level of significance, is there evidence of a significant difference between the two population proportions? b. Construct a 95% confidence interval estimate for the difference between the two p
> In a one-tail hypothesis test where you reject H0 only in the lower tail, what is the p-value if ZSTAT = +1.38?
> The file Concrete1 contains the compressive strength, in thousands of pounds per square inch (psi), of 40 samples of concrete taken two and seven days after pouring. Source: Data extracted from O. Carrillo-Gamboa and R. F. Gunst, “Measurement- Error-Mode
> To assess the effectiveness of a cola video ad, a random sample of 38 individuals from a target audience was selected to participate in a copy test. Participants viewed two ads, one of which was the ad being tested. Participants then answered a series of
> Multiple myeloma, or blood plasma cancer, is characterized by increased blood vessel formulation (angiogenesis) in the bone marrow that is a predictive factor in survival. One treatment approach used for multiple myeloma is stem cell transplantation with
> How do the fares for airlines that directly compete compare? The file Airlines contains roundtrip fares for nonstop travel from Philadelphia to 10 different U.S. destinations on Southwest Airlines and American Airlines that a frequent flyer collected. So
> Does LTE network performance vary between providers? The file LTE contains the download speed (in Mbps) on LTE connections of AT&T and Verizon providers in 31 U.S. large metro markets. Source: Data extracted from State of Mobile Networks: USA, August 201
> How do the ratings of TV and Internet services compare? The file Telecom contains the rating of 10 different providers. Source: Data extracted from ACSI Telecommunication Report 2017, available at bit.ly/2syfcbA. a. At the 0.05 level of significance, is
> A survey of nonprofit organizations showed that online fundraising has increased in the past year. Based on a random sample of 133 nonprofits, the mean one-time gift donation resulting from email outreach in the past year was $87. Assume that the sample
> Nine experts rated two brands of coffee in a taste-testing experiment. A rating on a 7-point scale (1 = extremely unpleasing, 7 = extremely pleasing) is given for each of four characteristics: taste, aroma, richness, and acidity. The following data store
> Fifteen volunteers are recruited to participate in an experiment. A measurement is made (such as blood pressure) before each volunteer is asked to read a particularly upsetting passage from a book and after each volunteer reads the passage from the book.
> An experimental design for a paired t test has 20 pairs of identical twins. How many degrees of freedom are there in this t test?
> In Problem 9.38, what is your statistical decision if you test the null hypothesis at the 0.01 level of significance? Problem 9.38: In a one-tail hypothesis test where you reject H0 only in the lower tail, what is the p-value if ZSTAT = -1.38?
> Brand valuations are critical to CEOs, financial and marketing executives, security analysts, institutional investors, and others who depend on well-researched, reliable information needed for assessments, and comparisons in decision making. Millward Bro
> We Are Social and Hootsuite reported that the typical American spends 2.02 hours (121 minutes) per day accessing the Internet through a mobile device. Source: Digital in 2017 Global Overview, available at bit.ly/2jXeS3F. You wonder if males and females s
> Repeat Problem 10.14 (a), assuming that the population variances from developed and emerging countries are not equal. Compare these results with those of Problem 10.14 (a).
> As a member of the international strategic management team in your company, you are assigned the task of exploring potential foreign market entry. As part of your initial investigation, you want to know if there is a difference between developed markets
> Repeat Problem 10.12 (a), assuming that the population variances in the two branches are not equal. Compare these results with those of Problem 10.12 (a). Problem 10.12: A bank with a branch located in a commercial district of a city has the business ob
> A bank with a branch located in a commercial district of a city has the business objective of developing an improved process for serving customers during the noon-to-1 p.m. lunch period. Management decides to first study the waiting time in the current p
> The annual NFL Super Bowl is the most widely watched sporting event in the United States each year. In recent years, there has been a great deal of interest in the ads that appear during the game. These ads vary in length with most lasting 30 seconds or
> A marketing researcher wants to estimate the mean amount spent ($) on Amazon.com by Amazon Prime member shoppers. Suppose a random sample of 100 Amazon Prime member shoppers who recently made a purchase on Amazon.com yielded a mean of $1,500 and a standa
> Accounting Today identified the top accounting firms in 10 geographic regions across the United States. All 10 regions reported growth in 2016. The Southeast and Gulf Coast regions reported growth of 12.03% and 9.47%, respectively. A characteristic descr
> Is there a difference in the satisfaction rating of traditional cellphone providers who bill for service at the end of a month often under a contract and prepaid cellphone service providers who bill in advance without a contract? The file CellphoneProvid
> In a one-tail hypothesis test where you reject H0 only in the lower tail, what is the p-value if ZSTAT = -1.38?
> A recent study found that 51 children who watched a commercial for Walker Crisps (potato chips) featuring a long-standing sports celebrity endorser ate a mean of 36 grams of Walker Crisps as compared to a mean of 25 grams of Walker Crisps for 41 children
> When people make estimates, they are influenced by anchors to their estimates. A study was conducted in which students were asked to estimate the number of calories in a cheeseburger. One group was asked to do this after thinking about a calorie-laden ch
> If you have samples of n1 = 12 and n2 = 15, in performing the pooled-variance t test, how many degrees of freedom do you have?
> Financial institutions utilize prediction models to predict bankruptcy. One such model is the Altman Z-score model, which uses multiple corporate income and balance sheet values to measure the financial health of a company. If the model predicts a low Z-
> In Problem 9.36, what is your statistical decision if you test the null hypothesis at the 0.05 level of significance? Problem 9.36: In a one-tail hypothesis test where you reject H0 only in the upper tail, what is the p-value if ZSTAT = +2.00?
> In hypothesis testing, the common level of significance is α = 0.05. Some might argue for a level of significance greater than 0.05. Suppose that web designers tested the proportion of potential web page visitors with a preference for a new web design ov
> What is the five-step p-value approach to hypothesis testing?
> What is the six-step critical value approach to hypothesis testing?
> How can a confidence interval estimate for the population mean provide conclusions for the corresponding two-tail hypothesis test for the population mean?
> What is meant by a p-value?
> What is the difference between a one-tail test and a two-tail test?
> What is meant by the power of a test?
> What is the difference between a Type I error and a Type II error?
> What is the difference between a null hypothesis, H0, and an alternative hypothesis, H1?
> Assuming that the population is normally distributed, construct a 95% confidence interval estimate for the population mean for each of the following samples: Sample A: 1 1 1 1 8 8 8 8 Sample B: 1 2 3 4 5 6 7 8 Explain why these two samples produce diff
> In a one-tail hypothesis test where you reject H0 only in the upper tail, what is the p-value if ZSTAT = +2.00?
> Actuation Consulting conducted a global survey of product teams with the goal of better understanding the dynamics of product team performance and uncovering the practices that make these teams successful. Having a clear definition of “done” is a basic e
> A cellphone provider has the business objective of wanting to determine the proportion of subscribers who would upgrade to a new cellphone with improved features if it were made available at a substantially reduced cost. Data are collected from a random
> What are companies’ biggest obstacles to attracting the best talent? Of 703 surveyed U.S. and Canadian talent acquisition professionals, 464 reported that competition for talent is the biggest obstacle at their company. Source: U.S. and Canadian Recruiti
> One of the issues facing organizations is increasing diversity throughout an organization. One of the ways to evaluate an organization’s success at increasing diversity is to compare the percentage of employees in the organization in a particular positio
> The worldwide market share for the Chrome web browser was 56.43% in a recent month. Source: Data extracted from netmarketshare.com. Suppose that you decide to select a sample of 100 students at your university and you find that 60 use the Chrome web brow
> According to a recent National Association of Colleges and Employers (NACE) report, 44% of college students who had unpaid internships received full-time job offers post-graduation compared to 72% of college students who had paid internships. Source: Dat
> In Problems 9.52 and 9.53, suppose you are testing the null hypothesis H0: π = 0.20 against the two-tail alternative hypothesis H1: π ≠ 0.20 and you choose the level of significance α = 0.05. What is your statistical decision? Problem 9.53: In Problem
> In Problem 9.52, if the null hypothesis is that 20% of the items in the population are defective, what is the value of ZSTAT? Problem 9.52: If, in a random sample of 400 items, 88 are defective, what is the sample proportion of defective items?
> The following data (in Drink ) represent the amount of soft drink filled in a sample of 50 consecutive 2-liter bottles. The results, listed horizontally in the order of being filled, were: 2.109 2.086 2.066 2.075 2.065 2.057 2.052 2.044 2.036 2.038 2.03
> An insurance company has the business objective of reducing the amount of time it takes to approve applications for life insurance. The approval process consists of underwriting, which includes a review of the application, a medical information bureau ch
> The file FastFood contains the amount that a sample of fifteen customers spent for lunch ($) at a fast-food restaurant: 7.42 6.29 5.83 6.50 8.34 9.51 7.10 6.80 5.90 4.89 6.50 5.52 7.90 8.30 9.60 a. At the 0.05 level of significance, is there evidence tha
> If, in a random sample of 400 items, 88 are defective, what is the sample proportion of defective items?
> The U.S. Department of Transportation requires tire manufacturers to provide performance information on tire sidewalls to help prospective buyers make their purchasing decisions. One very important piece of information is the tread wear index, which indi
> A marketing researcher wants to estimate the mean amount spent per year ($) on Amazon.com by Amazon Prime member shoppers. Suppose a random sample of 100 Amazon Prime member shoppers who recently made a purchase on Amazon.com yielded a mean amount spent
> A manufacturer of chocolate candies uses machines to package candies as they move along a filling line. Although the packages are labeled as 8 ounces, the company wants the packages to contain a mean of 8.17 ounces so that virtually none of the packages
> You are the manager of a restaurant for a fast-food franchise. Last month, the mean waiting time at the drive-through window for branches in your geographic region, as measured from the time a customer places an order until the time the customer receives
> A bottled water distributor wants to estimate the amount of water contained in 1-gallon bottles purchased from a nationally known water bottling company. The water bottling company’s specifications state that the standard deviation of the amount of water
> The population mean waiting time to check out of a supermarket has been 4 minutes. Recently, in an effort to reduce the waiting time, the supermarket has experimented with a system in which infrared cameras use body heat and in-store software to determin
> We Are Social and Hootsuite reported that the typical American spends 2.02 hours (121 minutes) per day accessing the Internet via mobile devices. Source: Digital in 2017 Global Overview, available at bit.ly/2jXeS3F. In order to test the validity of this
> Suppose that in Problem 9.16, the standard deviation is 0.012 gallon. a. Repeat (a) through (d) of Problem 9.16, assuming a standard deviation of 0.012 gallon. b. Compare the results of (a) to those of Problem 9.16.
> A bottled water distributor wants to determine whether the mean amount of water contained in 1-gallon bottles purchased from a nationally known water bottling company is actually 1 gallon. You know from the water bottling company specifications that the
> Suppose that in Problem 9.14, the standard deviation is 500 hours. a. Repeat (a) through (d) of Problem 9.14, assuming a standard deviation of 500 hours. b. Compare the results of (a) to those of Problem 9.14.
> The quality-control manager at a light emitting diode (LED) factory needs to determine whether the mean life of a large shipment of LEDs is equal to 50,000 hours. The population standard deviation is 1,500 hours. A random sample of 64 LEDs indicates a sa
> Do business seniors at your school prepare for class more than, less than, or about the same as business seniors at other schools? The National Survey of Student Engagement (NSSE) annual results, available at bit.ly/1j3Ob7N, found that business seniors s
> As a result of complaints from both students and faculty about lateness, the registrar at a large university is ready to undertake a study to determine whether the scheduled break between classes should be changed. Until now, the registrar has believed t
> Many consumer groups feel that the U.S. Food and Drug Administration (FDA) drug approval process is too easy and, as a result, too many drugs are approved that are later found to be unsafe. On the other hand, a number of industry lobbyists have pushed fo
> You are working as an assistant to the dean of institutional research at your university. The dean wants to survey members of the alumni association who obtained their baccalaureate degrees five years ago to learn what their starting salaries were in the
> Suppose the defendant in Problem 9.9 is presumed guilty until proven innocent. How do the null and alternative hypotheses differ from those in Problem 9.9? What are the meanings of the risks of committing either a Type I or Type II error here?
> Determine the critical value of t in each of the following circumstances: a. 1 - α = 0.95, n = 10 b. 1 - α = 0.99, n = 10 c. 1 - α = 0.95, n = 32 d. 1 - α = 0.95, n = 65 e. 1 - α = 0.90, n = 16
> In the U.S. legal system, a defendant is presumed innocent until proven guilty. Consider a null hypothesis, H0, that a defendant is innocent, and an alternative hypothesis, H1, that the defendant is guilty. A jury has two possible decisions: Convict the
> What is the p-value if, in a two-tail hypothesis test, ZSTAT = -1.38?
> In Problem 9.6, what is your statistical decision if you test the null hypothesis at the 0.10 level of significance? Problem 9.6: What is the p-value if, in a two-tail hypothesis test, ZSTAT = +2.00?
> What is the p-value if, in a two-tail hypothesis test, ZSTAT = +2.00?
> What is your decision in Problem 9.4 if ZSTAT = -2.61? Problem 9.4: If you use a 0.01 level of significance in a two-tail hypothesis test, what is your decision rule for rejecting H0 :μ = 12.5 if you use the Z test?
> If you use a 0.01 level of significance in a two-tail hypothesis test, what is your decision rule for rejecting H0 :μ = 12.5 if you use the Z test?
> If you use a 0.10 level of significance in a two-tail hypothesis test, what is your decision rule for rejecting a null hypothesis that the population mean equals 500 if you use the Z test?
> If you use a 0.05 level of significance in a two-tail hypothesis test, what decision will you make if ZSTAT = +2.21?
> If you use a 0.05 level of significance in a two-tail hypothesis test, what decision will you make if ZSTAT = -0.76?
