Question: Determine whether there are violations of the

> The manager of a tire store in Minneapolis has been concerned with the high cost of inventory. The current policy is to stock all the snow tires that are predicted to sell over the entire winter at the beginning of the season (end of October). The manage

> Refer to Exercise 16.131. Determine whether there is evidence of first-order autocorrelation. Data from Exercise 16.131: The manager of Colonial Furniture has been reviewing weekly advertising expenditures. During the past 6 months, all advertisements f

> Refer to Exercise 17.3. Is there evidence of positive first-order autocorrelation? Data from Exercise 17.3: The president of a company that manufactures drywall wants to analyze the variables that affect demand for his product. Drywall is used to constr

> Weekly sales of a company’s product (y) and those of its main competitor (x) were recorded for one year. a. Conduct a regression analysis of these data. b. Plot the residuals versus the time periods. Does there appear to be autocorrelation? c. Perform th

> Observations of variables y, x1, and x2 were taken over 100 consecutive time periods. a. Conduct a regression analysis of these data. b. Plot the residuals versus the time periods. Describe the graph. c. Perform the Durbin-Watson test. Is there evidence

> Test the following hypotheses with  = .05. H0: There is no first-order autocorrelation. H1: There is negative first-order autocorrelation. n = 33, k = 4, d = 2.25

> The widespread use of salt on roads in Canada and the northern United States during the winter and acid precipitation throughout the year combine to cause rust on cars. Car manufacturers and other companies offer rustproofing services to help purchasers

> After a recent study, researchers reported on the effects of folic acid on the occurrence of spina bifida—a birth defect in which there is incomplete formation of the spine. A sample of 2,000 women who gave birth to children with spina bifida and who wer

> Test the following hypotheses with = .02. H0: There is no first-order autocorrelation. H1: There is first-order autocorrelation. n = 90, k = 5, d = 1.60

> Test the following hypotheses with  = .05. H0: There is no first-order autocorrelation. H1: There is positive first-order autocorrelation. n = 50, k = 2, d = 1.38

> When one company buys another company, it is not unusual that some workers are terminated. The severance benefits offered to the laid-off workers are often the subject of dispute. Suppose that the Laurier Company recently bought the Western Company and s

> Given the following information, perform the Durbin-Watson test to determine whether first order autocorrelation exists: n = 25, k = 5,= .10, d = .90

> Exercise 13.19 described a survey that asked people between 18 and 34 years of age and 35 to 50 years of age how much time they spent listening to FM radio each day. Also recorded were the amounts spent on music throughout the year. Can we infer that a l

> In addition to the data recorded for Exercises 12.31 and 13.227, we recorded the grade point average of the students who held down parttime jobs. Determine whether there is evidence of a linear relationship between the hours spent at parttime jobs and th

> A computer dating service typically asks for various pieces of information such as height, weight, income, and so on. One such service requested the length of index fingers. The only plausible reason for this request is to act as a proxy on height. Women

> (Exercise 3.67 revisited) A very large contribution to profits for a movie theater is the sale of popcorn, soft drinks, and candy. A movie theater manager speculated that the longer the time between showings of a movie, the greater the sales of concessio

> Mutual funds minimize risks by diversifying the investments they make. There are mutual funds that specialize in particular types of investments. For example, the TD Precious Metal Mutual Fund buys shares in gold mining companies. The value of this mutua

> The analysis that the human resources manager performed in Exercise 16.18 indicated that the dexterity test is not a predictor of job performance. However, before discontinuing the test, he decided that the problem is that the statistical analysis was fl

> Automobile insurance appraisers examine cars that have been involved in accidental collisions and estimate the cost of repairs. An insurance executive claims that there are significant differences in the estimates from different appraisers. To support hi

> Some critics of television complain that the amount of violence shown on television contributes to violence in our society. Others point out that television also contributes to the high level of obesity among children. We may have to add financial proble

> Every year, the U.S. Federal Trade Commission rates cigarette brands according to their levels of tar and nicotine, substances that are hazardous to smokers’ health. Additionally, the commission includes the amount of carbon monoxide, which is a by-produ

> An agronomist wanted to investigate the factors that determine crop yield. Accordingly, she undertook an experiment wherein a farm was divided into 30 one-acre plots. The amount of fertilizer applied to each plot was varied. Corn was then planted, and th

> The president of a company that manufactures car seats has been concerned about the number and cost of machine breakdowns. The problem is that the machines are old and becoming quite unreliable. However, the cost of replacing them is quite high, and the

> The manager of Colonial Furniture has been reviewing weekly advertising expenditures. During the past 6 months, all advertisements for the store have appeared in the local newspaper. The number of ads per week has varied from one to seven. The store’s sa

> Perform a complete diagnostic analysis for Exercise 16.18 to determine whether the required conditions are satisfied.

> Are the required conditions satisfied for Exercise 16.17?

> Check to ensure that the required conditions for Exercise 16.16 are satisfied.

> Are the required conditions satisfied for Exercise 16.15?

> Refer to Exercise 16.14. a. Determine the residuals and the standardized residuals. b. Draw the histogram of the residuals. Does it appear that the errors are normally distributed? Explain. c. Identify possible outliers. d. Plot the residuals versus the

> Most automobile repair shops now charge according to a schedule that is claimed to be based on average times. This means that instead of determining the actual time to make a repair and multiplying this value by their hourly rate, repair shops determine

> Refer to Exercise 16.13. Are the required conditions satisfied? Data from Exercise 16.13: Millions of boats are registered in the United States. As is the case with automobiles, there is an active used-boat market. Many of the boats purchased require ba

> Check the required conditions for Exercise 16.12.

> Refer to Exercise 16.11. a. Determine the residuals and the standardized residuals. b. Draw the histogram of the residuals. Does it appear that the errors are normally distributed? Explain. c. Identify possible outliers. d. Plot the residuals versus the

> Refer to Exercise 16.10. Are the required conditions satisfied? Data from Exercise 16.10: Besides their known long-term effects, do cigarettes also cause short-term illnesses such as colds? To help answer this question, a sample of smokers was drawn. Ea

> Determine whether negative first-order autocorrelation exists when d = 2.85, n = 50, and k = 5. (Use a 1% significance level.)

> Are the required conditions satisfied in Exercise 16.8?

> Perform the Durbin-Watson test at the 5% significance level to determine whether positive first-order autocorrelation exists when d = 1.10, n = 25, and k = 3.

> Refer to Exercise 17.16. Are the required conditions satisfied? Data from Exercise 17.16: The pollster also recorded the following variables in addition to the variable DEFINITE. Number of days in previous week watching national news on television (DAYS

> Calculate and plot the residuals and predicted values of y for Exercise 16.5.

> Refer to Exercise 16.4. a. Calculate the residuals. b. Calculate the predicted values of y. c. Plot the residuals (on the vertical axis) and the predicted values of y. Data from Exercise 16.4: Critics of television often refer to the detrimental effects

> Discrimination in hiring has been illegal for many years. It is illegal to discriminate against any person on the basis of race, gender, or religion. It is also illegal to discriminate because of a person’s handicap if it in no way prevents that person f

> Calculate the residuals and predicted values of y in Exercise 16.3.

> Refer to Exercise 16.2. Calculate the residuals and the predicted values of y. Data from Exercise 16.2: Attempting to analyze the relationship between advertising and sales, the owner of a furniture store recorded the monthly advertising budget ($ thous

> You are given the following six points: a. Determine the regression equation. b. Use the regression equation to determine the predicted values of y. c. Use the predicted and actual values of y to calculate the residuals. d. Compute the standardized resi

> Refer to Exercise 17.15. Determine whether the required conditions are satisfied. Data from Exercise 17.15: With voter turnout during presidential elections around 50%, a vital task for politicians is to try to predict who will actually vote. A variable

> Refer to Exercise 17.15. Check the required conditions. Data from Exercise 17.15: With voter turnout during presidential elections around 50%, a vital task for politicians is to try to predict who will actually vote. A variable used to determine who is

> The general manager of the Cleveland Indians baseball team is in the process of determining which minor-league players to draft. He is aware that his team needs home-run hitters and would like to find a way to predict the number of home runs a player wil

> Refer to Exercise 17.14. Are the required conditions satisfied? Data from Exercise 17.14: The MBA program at a large university is facing a pleasant problem—too many applicants. The current admissions policy requires students to have completed at least

> Refer to Exercise 17.13. a. Are the required conditions satisfied? b. Is multicollinearity a problem? If so, explain the consequences. Data from Exercise 17.13: Lotteries have become important sources of revenue for governments. Many people have critici

> Refer to Exercise 17.10. Calculate the residuals and predicted values. a. Is the normality requirement satisfied? b. Is the variance of the error variable constant? c. Is multicollinearity a problem? Data from Exercise 17.10: Life insurance companies ar

> Health-care costs in the United States and Canada are concerns for citizens and politicians. The question is, How can we devise a system wherein people’s medical bills are covered but individuals attempt to reduce costs? An American company has come up w

> Determine whether the required conditions are satisfied in Exercise 17.9

> Are the required conditions satisfied for the regression analysis in Exercise 17.8?

> Refer to Exercise 17.7. a. Conduct an analysis of the residuals to determine whether any of the required conditions are violated. b. Does it appear that multicollinearity is a problem? c. Identify any observations that should be checked for accuracy. Da

> Are the required conditions satisfied in Exercise 17.6?

> Calculate the residuals and predicted values for the regression analysis in Exercise 17.5. a. Does the error variable appear to be normally distributed? b. Is the variance of the error variable constant? c. Is multicollinearity a problem?

> Pick any one of the previous five exercises and briefly describe why the intervals are so wide.

> Refer to Exercise 16.49. The temperature is 80 degrees. Predict with 95% confidence how far the golfer’s next drive will travel. Data from Exercise 16.49: Refer to Exercise 3.71 wherein we looked at the relationship between temperature and distance that

> Refer to Exercise 16.48. Predict with 90% confidence how definite is the intention to vote for one 50-year-old. Data from Exercise 16.48: In most presidential elections in the United States, the voter turnout is quite low, often in the neighborhood of 5

> Refer to Exercise 16.47. Estimate with 90% confidence the mean number of days watching the national news on television for the population of 70-year-olds. Data from Exercise 16.47: National news on television features commercials describing pharmaceutic

> Refer to Exercise 16.46. Use a prediction interval with 90% confidence to predict the auction selling price of one Canada 1925 nickel with a grade of 40. Data from Exercise 16.46: Refer to Exercise 3.70 where we looked at the relationship between the gr

> A study was undertaken to determine whether a drug commonly used to treat epilepsy could help alcoholics to overcome their addiction. The researchers took a sample of 103 hardcore alcoholics. Fifty-five drinkers were given topiramate and the remaining

> Refer to Exercise 16.45. Estimate with 95% confidence the mean time spent watching or reading news on the Internet for the population of people who have completed 12 years of education. Data from Exercise 16.45: Do more educated people spend more time w

> Refer to Exercise 16.18. Estimate with 95% confidence the mean percentage of defectives for workers who score 80 on the dexterity test. Data from Exercise 16.18: Although a large number of tasks in the computer industry are robotic, many operations requ

> Refer to Exercise 16.17. a. Estimate with 95% confidence the mean annual income of 6’2” (74 inches)-tall men. b. Suppose that an individual is 5’8” (68 inches). Predict with 95% confidence his annual income. Data from Exercise 16.17: One general belief

> Refer to Exercise 16.16. Predict with 95% confidence the monthly office rent in a city when the vacancy rate is 8%. Data from Exercise 16.16: An economist wanted to investigate the relationship between office rents (the dependent variable) and vacancy r

> Refer to Exercise 16.15. Predict the food budget of a family whose household income is $60,000. Use a 90% confidence level. Data from Exercise 16.15: An economist for the federal government is attempting to produce a better measure of poverty than is cu

> Refer to Exercise 16.14. Estimate with 90% confidence the mean electricity consumption for households with four occupants. Data from Exercise 16.14: In an attempt to determine the factors that affect the amount of energy used, 200 households were analyz

> Refer to Exercise 16.13. Predict with 99% confidence the price of a 1999 24-ft. Sea Ray cruiser with 400 hours of engine use. Data from Exercise 16.13: Millions of boats are registered in the United States. As is the case with automobiles, there is an a

> Refer to Exercise 16.12. Estimate with 95% confidence the mean price of 60,000 sq.ft. apartment buildings. Data from Exercise 16.12: A real estate agent specializing in commercial real estate wanted a more precise method of judging the likely selling pr

> Refer to Exercise 16.11. a. Predict with 95% confidence the percentage loss due to fire for a house that is 8 miles away from the nearest fire station. b. Estimate with 95% confidence the average percentage loss due to fire for houses that are 5 miles aw

> Refer to Exercise 16.10. Predict with 95% confidence the number of sick days for individuals who smoke on average 40 cigarettes per day. Data from Exercise 16.10: Besides their known long-term effects, do cigarettes also cause short-term illnesses such

> A professor of statistics hands back his graded midterms in class by calling out the name of each student and personally handing the exam over to its owner. At the end of the process, he notes that there are several exams left over, the result of student

> Refer to Exercise 16.9. The company has just hired a 22-year-old telemarketer. Predict with 95% confidence how long he will stay with the company. Data from Exercise 16.9: The human resource manager of a telemarketing firm is concerned about the rapid t

> Refer to Exercise 16.8. Estimate with 90% confidence the mean amount of time for 40-year-old Americans to complete the census. Data from Exercise 16.8: In 2010, the United States conducted a census of the entire country. The census is completed by mail.

> Refer to Exercise 16.7. a. Predict with 95% confidence the selling price of a 1,200 sq.ft. condominium on the 20 th floor. b. Estimate with 99% confidence the average selling price of a 1,200 sq.ft. condominium on the 15th floor. Data from Exercise 16.7

> Refer to Exercise 16.6. a. Predict with 95% confidence the memory test score of a viewer who watches a 30-second commercial. b. Estimate with 95% confidence the mean memory test score of people who watch 30-second commercials. Data from Exercise 16.6: I

> Refer to Exercise 16.5. Predict with 90% confidence the number of beers to be sold when the temperature is 75 degrees. Data from Exercise 16.5: To help determine how many beers to stock the concession manager at Yankee Stadium wanted to know how the tem

> Refer to Exercise 16.4. a. Predict with 90% confidence the number of pounds overweight for a child who watches 35 hours of television per week. b. Estimate with 90% confidence the mean number of pounds overweight for children who watch 35 hours of televi

> Estimate with 90% confidence the mean monthlynumber of housing starts when the mortgage interest rate is 7% in Exercise 16.3.

> Use the regression equation in Exercise 16.2 to predict with 90% confidence the sales when the advertising budget is $80,000.

> Will the prediction interval always be wider than the estimation interval for the same value of the independent variable? Briefly explain.

> Briefly describe the difference between predicting a value of y and estimating the expected value of y.

> Advertising is critical in the residential real estate industry. Agents are always seeking ways to increase sales through improved advertising methods. A particular agent believes that he can increase the number of inquiries (and thus the probability of

> The president of a company that manufactures drywall wants to analyze the variables that affect demand for his product. Drywall is used to construct walls in houses and offices. Consequently, the president decides to develop a regression model in which t

> Refer to Exercise 17.4. Find the coefficients of correlation of the independent variables. a. What do these correlations tell you about the independent variables? b. What do they say about the t-tests of the coefficients? Data from Exercise 17.4: The ge

> Compute the residuals and predicted values for the regression analysis in Exercise 17.3. a. Does it appear that the error variable is not normally distributed? b. Is the variance of the error variable constant? c. Is multicollinearity a problem?

> Calculate the coefficients of correlation for each pair of independent variables in Exercise 17.1. What do these statistics tell you about the independent variables and the t-tests of the coefficients?

> Compute the residuals and the predicted values for the regression analysis in Exercise 17.1. a. Is the normality requirement violated? Explain. b. Is the variance of the error variable constant? Explain.

> Pat Statsdud, a student ranking near the bottom of the statistics class, decided that a certain amount of studying could actually improve final grades. However, too much studying would not be warranted because Pat’s ambition (if that’s what one could cal

> La Quinta Motor Inns is a moderately priced chain of motor inns located across the United States. Its market is the frequent business traveler. The chain recently launched a campaign to increase market share by building new inns. The management of the ch

> Refer to Exercise 17.15. The pollster also recorded the following variables in addition to the variable DEFINITE. Number of days in previous week watching national news on television (DAYS1) Number of days in previous week watching local television news

> With voter turnout during presidential elections around 50%, a vital task for politicians is to try to predict who will actually vote. A variable used to determine who is likely to vote was created and defined as follows. DEFINITE: 1 = Definitely will no

> The MBA program at a large university is facing a pleasant problem—too many applicants. The current admissions policy requires students to have completed at least 3 years of work experience and an undergraduate degree with a B-average or better. Until 3

> Sales of a product may depend on its placement in a store. Candy manufacturers frequently offer discounts to retailers who display their products more prominently than competing brands. To examine this phenomenon more carefully, a candy manufacturer (wit

> Lotteries have become important sources of revenue for governments. Many people have criticized lotteries, however, referring to them as a tax on the poor and uneducated. In an examination of the issue, a random sample of 100 adults was asked how much th

> One critical factor that determines the success of a catalog store chain is the availability of products that consumers want to buy. If a store is sold out, future sales to that customer are less likely. Accordingly, delivery trucks operating from a cent

> University students often complain that universities reward professors for research but not for teaching, and they argue that professors react to this situation by devoting more time and energy to the publication of their findings and less time and energ

> Life insurance companies are keenly interested in predicting how long their customers will live because their premiums and profitability depend on such numbers. An actuary for one insurance company gathered data from 100 recently deceased male customers.

> A developer who specializes in summer cottage properties is considering purchasing a large tract of land adjoining a lake. The current owner of the tract has already subdivided the land into separate building lots and has prepared the lots by removing so