One measure of the state of the economy is the amount of money homeowners pay on their mortgage each month. To determine the extent of change between this year and 5 years ago, a random sample of 150 homeowners was drawn. The monthly mortgage payments for each homeowner for this year and for 5 years ago were recorded. (The amounts have been adjusted so that we’re comparing constant dollars.) Can we infer that mortgage payments have risen over the past 5 years?
> Consider a multinomial experiment involving n = 150 trials and k = 4 cells. The observed frequencies resulting from the experiment are shown in the accompanying table, and the null hypothesis to be tested is as follows: H0: p1 = .3, p2 = .3, p3 = .2, p4
> Diners at a restaurant were informed on entering that they would be receiving a free glass of wine, which they were told was Cabernet Sauvignon. However, it was not. It was a cheap wine sold for $2 a bottle, popularly known as Two Buck Chuck. Half of the
> Students were invited to watch a newly released movie shortly after lunch. Half the students were given a medium-sized bucket of popcorn and the other half a large-sized bucket. The popcorn was not fresh. In fact, it was five days old and very stale. Bot
> Studies have shown that tired children have trouble learning because neurons become incapable of forming new synaptic connections that are necessary to encode memory. The problem is that the school day starts too early. Awakened at dawn, teenage brains a
> Traditionally, wine has been sold in glass bottles with cork stoppers. The stoppers are supposed to keep air out of the bottle because oxygen is the enemy of wine, particularly red wine. Recent research appears to indicate that metal screw caps are more
> Credit scorecards were designed to be used to help financial institutions make decisions about loan applications. However, some insurance companies have suggested that credit scores could also be used to determine insurance premiums, particularly car ins
> It is generally believed that salespeople who are paid on a commission basis outperform salespeople who are paid a fixed salary. Some management consultants argue, however, that in certain industries the fixed-salary salesperson may sell more because the
> Tire manufacturers are constantly researching ways to produce tires that last longer. New innovations are tested by professional drivers on racetracks. However, any promising inventions are also test-driven by ordinary drivers. The latter tests are close
> It is often useful for companies to know who their customers are and how they became customers. In a study of credit card use, random samples were drawn of cardholders who applied for the credit card and credit cardholders who were contacted by telemarke
> Lack of sleep is a serious medical problem. It has been linked to heart attacks and automobile collisions. A Statistics Canada study asked a random sample of Canadian adults to report the amount of sleep they normally get. Can we conclude from the data t
> Between Wendy’s and McDonald’s, which fast-food drive-through window is faster? To answer the question, a random sample of service times for each restaurant was measured. Can we infer from these data that there are differences in service times between th
> Conduct a test to determine whether the two classifications R and C are independent, using the data in the accompanying cross-classification table. (Use  = .10.) C3 R, R2 40 32 48 30 48 52
> The following statistics were calculated: a. Complete the ANOVA table. b. Repeat part (a) changing the sample means to 130, 135, 133, and 140. c. Describe the effect on the F-statistic of increasing the sample means by 100. Treatment Statistic 1 2 3
> A study by researchers at North Carolina State University found thousands of errors in 12 of the most widely used high school science texts. For example, the Statue of Liberty is left-handed; volume is equal to length multiplied by depth. The books are s
> Most consumers who require someone to perform various professional services undertake research before making their selection. A random sample of people who recently selected a financial planner and a random sample of individuals who chose a stockbroker w
> Refer to Exercise 13.26. To determine whether the type of phone usage affects reaction times, another study was launched. A group of drivers was asked to participate in a discussion. Half the group engaged in simple chitchat, and the other half participa
> Recent studies seem to indicate that using a cell phone while driving is dangerous. One reason for this is that a driver’s reaction time may slow while he or she is talking on the phone. Researchers at Miami (Ohio) University measured the reaction times
> After determining in Exercise 13.229 that teenagers watch more movies than do 20–30-year-olds, teenagers were further segmented into three age groups: 12 to 14, 15 to 16, and 17 to 19. Random samples were drawn from each segment, and the number of movies
> You are given the following statistics: a. Complete the ANOVA table. b. Repeat part (a) changing the variances to 25 each. c. Describe the effect on the F-statistic of increasing the sample variances. Treatment Statistic 1 2 n 4 4 4 20 22 25 10 10 1
> A manufacturer of novelty items is undecided about the price to charge for a new product. The marketing manager knows that it should sell for about $10 but is unsure of whether sales will vary significantly if it is priced at either $9 or $11. To conduct
> There is a bewildering number of breakfast cereals on the market. Each company produces several different products in the belief that there are distinct markets. For example, there is a market composed primarily of children, another for diet-conscious ad
> In 1994, the chief executive officers of the major tobacco companies testified before a U.S. Senate subcommittee. One of the accusations made was that tobacco firms added nicotine to their cigarettes, which made them even more addictive to smokers. Compa
> Review the results of Exercises 15.26–15.28. What is the effect of decreasing the sample size?
> Does the level of success of publicly traded companies affect the way their board members are paid? Publicly traded companies were divided into four quarters using the rate of return in their stocks to differentiate among the companies. The annual paymen
> A study performed by a Columbia University professor (described in Report on Business, August 1991) counted the number of times per minute professors from three different departments said “uh” or “ah” during lectures to fill gaps between words. The data
> In the introduction to this chapter, we mentioned that the first use of the analysis of variance was in the 1920s. It was employed to determine whether different amounts of fertilizer yielded different amounts of crop. Suppose that a scientist at an agri
> In early 2001, the economy was slowing down and companies were laying off workers. A Gallup poll asked a random sample of workers how long it would be before they had significant financial hardships if they lost their jobs and couldn’t find new ones. The
> A manufacturer of outdoor brass lamps and mailboxes has received numerous complaints about premature corrosion. The manufacturer has identified the cause of the problem as the low-quality lacquer used to coat the brass. He decides to replace his current
> A paint manufacturer is attempting to improve the process that fills the 1-gallon containers. The foreperson has suggested that the nozzle can be made from several different alloys. Furthermore, the way that the process “knows” when to stop the flow of p
> The headrests on a car’s front seats are designed to protect the driver and front-seat passenger from whiplash when the car is hit from behind. The frame of the headrest is made from metal rods. A machine is used to bend the rod into a U-shape exactly 44
> Are proficiency test scores affected by the education of the child’s parents? (Proficiency tests are administered to a sample of students in private and public schools. Test scores can range from 0 to 500.) To answer this question, a random sample of 9-y
> Most college instructors prefer to have their students participate actively in class. Ideally, students will ask their professor questions and answer their professor’s questions, making the classroom experience more interesting and usef
> Headaches are one of the most common, but least understood, ailments. Most people get headaches several times per month; overthe- counter medication is usually sufficient to eliminate their pain. However, for a significant proportion of people, headaches
> Repeat Exercise 15.26 using the following table: M, M2 7 17 14 9
> Detergent manufacturers frequently make claims about the effectiveness of their products. A consumer-protection service decided to test the five best selling brands of detergent, where each manufacturer claims that its product produces the “whitest white
> Refer to Exercise 14.10. Suppose that the experiment is redone in the following way. Thirty taxpayers fill out each of the four forms. However, 10 taxpayers in each group are in the lowest income bracket, 10 are in the next income bracket, and the remain
> Refer to Example 14.4. We’ve altered the data by subtracting 4 from the numbers of treatment 8. What do these data tell you? Data from Exercise 14.4: How does an MBA major affect the number of job offers received? An MBA student randomly sampled four re
> Refer to Example 14.4. We’ve revised the data by adding 2 to each of the numbers of the men. What do these data tell you? Data from Exercise 14.4: How does an MBA major affect the number of job offers received? An MBA student randomly sampled four recen
> The data shown here were taken from a 2 × 3 factorial experiment with 4 replicates: a. Test at the 5% significance level to determine whether factors A and B interact. b. Test at the 5% significance level to determine whether differences ex
> The following data were generated from a 2 × 2 factorial experiment with 3 replicates: a. Test at the 5% significance level to determine whether factors A and B interact. b. Test at the 5% significance level to determine whether differences
> A statistics practitioner conducted a two-factor analysis of variance experiment with a = 4, b = 3, and r = 8. The sums of squares are listed here: SS(Total) = 9420 SS(A) = 203 SS(B) = 859 SS(AB) = 513 a. Test at the 5% significance level to determine wh
> A two-factor analysis of variance experiment was performed with a = 3, b = 4, and r = 20. The following sums of squares were computed: SS(Total) = 42,450 SS(A) = 1,560 SS(B) = 2,880 SS(AB) = 7,605 Conduct whatever test you deem necessary at the 1% sig
> The friendly folks at the Internal Revenue Service (IRS) in the United States and Canada Revenue Agency (CRA) are always looking for ways to improve the wording and format of its tax return forms. Three new forms have been developed recently. To determin
> A statistics practitioner calculated the following statistics: a. Complete the ANOVA table. b. Repeat part (a) changing the sample sizes to 10 each. c. Describe what happens to the F-statistic when the sample sizes increase. Treatment Statistic 1 5
> Repeat Exercise 15.26 using the following table: M, M2 14 34 28 18
> The cost of health care is rising faster than most other items. To learn more about the problem a survey was undertaken to determine whether differences in health care expenditures exist between men and women. The survey randomly sampled men and women ag
> Because of the high cost of energy, homeowners in northern climates need to find ways to cut their heating costs. A building contractor wanted to investigate the effect on heating costs of increasing the insulation. As an experiment, he located a large s
> To determine the effect of advertising in the Yellow Pages, Bell Telephone took a sample of 40 retail stores that did not advertise in the Yellow Pages last year but did so this year. The annual sales (in thousands of dollars) for each store in both year
> Do waiters or waitresses earn larger tips? To answer this question, a restaurant consultant undertook a preliminary study. The study involved measuring the percentage of the total bill left as a tip for one randomly selected waiter and one randomly selec
> The president of a large company is in the process of deciding whether to adopt a lunchtime exercise program. The purpose of such programs is to improve the health of workers and, in so doing, reduce medical expenses. To get more information, he institut
> In an effort to determine whether a new type of fertilizer is more effective than the type currently in use, researchers took 12 two-acre plots of land scattered throughout the county. Each plot was divided into two equal-size subplots, one of which was
> In a preliminary study to determine whether the installation of a camera designed to catch cars that go through red lights affects the number of violators, the number of red-light runners was recorded for each day of the week before and after the camera
> The operations manager of a manufacturer of television remote controls wants to determine which batteries last the longest in his product. He took a random sample of his remote controls and tested two brands of batteries. Here are the number of minutes o
> How effective are antilock brakes, which pump very rapidly rather than lock and thus avoid skids? As a test, a car buyer organized an experiment. He hit the brakes and, using a stopwatch, recorded the number of seconds it took to stop an ABS-equipped car
> Conduct a test to determine whether the two classifications L and M are independent, using the data in the accompanying cross-classification table. (Use  = .05.) M, M2 28 68 56 36
> Many people use scanners to read documents and store them in a Word (or some other software) file. To help determine which brand of scanner to buy, a student conducts an experiment wherein eight documents are scanned by each of the two scanners in which
> Suppose that you are analyzing one of the hundreds of statistical studies linking smoking with lung cancer. The study analyzed thousands of randomly selected people, some of whom had lung cancer. The statistics indicate that those who have lung cancer sm
> You wish to determine whether MBA graduates who majored in finance attract higher starting salaries than MBA graduates who majored in marketing. a. Describe a data-gathering process that produces observational data. b. Describe a data-gathering process t
> Put yourself in place of the director of research and development for a pharmaceutical company. When a new drug is developed it undergoes a number of tests. One of the tests is designed to determine whether the drug is safe and effective. Your company ha
> Suppose that you wish to test to determine whether one method of teaching statistics is better than another. a. Describe a data-gathering process that produces observational data. b. Describe a data-gathering process that produces experimental data.
> Refer to Exercise 13.24. a. Are the data observational or experimental? b. If the data are observational, describe a method of answering the question with experimental data? c. If the data are observational, produce another explanation for the statistica
> The owner of a small book-publishing company is concerned about the declining number of people who read books. To learn more about the problem she takes a random sample of customers in a retail book store and asked each how many books they read in the la
> A human resources manager for a car company wanted to know whether production-line workers have more days absent than office workers. He took a random sample of eight workers from each category and recorded the number of days absent the previous year. Ca
> For each of the following, determine the number of degrees of freedom assuming equal population variances and unequal population variances. a. n1 = 15, n2 = 15, s21 = 25, s22 = 15 b. n1 = 10, n2 = 16, s21 = 100, s22 = 15 c. n1 = 50, n2 = 50, s21 = 8, s22
> Is there enough evidence to draw the inference that drivers of convertibles are less likely to honk? Following car was Following car was not a convertible a convertible Honked horn 21 86 Did not honk 92 210 horn
> One factor in low productivity is the amount of time wasted by workers. Wasted time includes time spent cleaning up mistakes, waiting for more material and equipment, and performing any other activity not related to production. In a project designed to e
> Can we conclude from these statistics that women are less likely to honk? Following car driver was female Following car driver was male Honked horn 68 105 Did not honk horn 143 135
> Is there sufficient evidence to infer that drivers behind a male driver are more likely to honk? Lead car driver was female Lead car driver was male Honked horn 64 47 Did not honk horn 123 136
> Expensive Car Experiment Do these figures allow us to conclude that drivers behind expensive cars are less likely to honk? Lead car was expen- Lead car was not sive (over $50,Õ00) expensive Honked horn 33 49 Did not honk 122 118 horn
> Cell Phone Experiment 2 Can we conclude that male drivers are more likely to honk when the lead car driver is using a cell phone? Driver in following Lead car driver Lead car driver did car was male used cell phone not use cell phone Honked horn 35
> Cell Phone Experiment 1 Is there enough evidence to infer that women drivers in a following car are more likely to honk when the lead car driver is using a cell phone? Driver in following Lead car driver Lead car driver not car was female using cell
> According to the Canadian Cancer Society more than 21,000 women will be diagnosed with breast cancer every year and more than 5,000 will die. (U.S. figures are more than 10 times those in Canada.) Surgery is generally considered the first method of treat
> In Exercise 12.110, the statistics practitioner also recorded the gender of the respondents, where 1 = Female and 2 = Male. Can we infer that men and women differ in their choices of Christmas trees?
> In addition to recording whether faculty members who are between 55 and 64 plan to retire before they reach 65 in Exercise 12.105, the consultant asked each to report his or her annual salary. Can the president infer that professors aged 55 to 64 who pla
> In Exercise 12.35, we described how the office equipment chain OfficeMax offers rebates on some products. The goal in that exercise was to estimate the total amount spent by customers who bought the package of 100 CD-ROMS. In addition to tracking these a
> The objective in the survey conducted in Example 12.6 was to estimate the size of the market segment of adults who are concerned about eating healthy foods. As part of the survey each respondent was asked how much they spend on breakfast cereal in an ave
> A statistics professor is about to select a statistical software package for her course. One of the most important features, according to the professor, is the ease with which students learn to use the software. She has narrowed the selection to two poss
> In addition to asking about educational attainment the survey conducted in Exercise 12.131 also asked whether the respondent had plans in the next 2 years to take a course (1 = No, 2 = Yes). Can we conclude that Californians who did not complete high sch
> Movie studios segment their markets by age. Two segments that are particularly important to this industry are teenagers and 20- to 30-year-olds. To assess markets and guide the making of movies, a random sample of teenagers and 20- to 30-year-olds was dr
> The company that organized the survey to determine the amount of discarded newspaper (Example 12.1) kept track of the type of neighborhood (1 = City, 2 = Suburbs). Do these data allow the company management to infer that city households discard more news
> Exercise 12.31 dealt with the amount of time high school students spend per week at parttime jobs. In addition to the hours of part-time work the school guidance counselor recorded the gender of the student surveyed (1 = Female, 2 = Male). Can we conclud
> At a camp cafeteria teenagers were randomly given a tall skinny glass or a short wide glass. As they proceeded through the line they loaded up on the food they wanted and poured whatever drink they chose. At the end of the line the quantity of drink they
> Refer to Exercise 13.224. Customers were also asked how likely they would return to the restaurant (2 = Likely, 1 = Unlikely). Is there enough evidence to infer that when the restaurant features bright lights and loud music customers are less likely to r
> A television program in conjunction with a researcher conducted a makeover of a Hardee’s Restaurant. The main room had bright lights and loud music. In a separate room, the renovation brought in plants, paintings, indirect lighting, and white tablecloths
> A researcher convinced a restaurant to experiment with two different kinds of music. One was faster upbeat music and the second was soft relaxing music. A random sample of diners was drawn and the type of music, the amount of time spent in the restaurant
> Are Americans more generous than Canadians? Random samples of American and Canadian tax returns were examined and whether it included a charitable donation were recorded (2 = Yes, 1 = No). Conduct a statistical test to answer the question.
> Refer to Exercise 12.143. The researchers also took a random sample of 702 cars last year. Is there sufficient evidence to conclude that American cars this year are on average older than cars last year? Data from Exercise 12.143: An important factor in
> An important function of a firm’s human resources manager is to track worker turnover. As a general rule, companies prefer to retain workers. New workers frequently need to be trained, and it often takes time for new workers to learn how to perform their
> In 2005 Larry Summers, then president of Harvard University received an avalanche of criticism for his attempt to explain why in mathematics there are more male professors than female professors. His suggested that there were innate differences that migh
> An inspector for the Atlantic City Gaming Commission suspects that a particular blackjack dealer may be cheating (in favor of the casino) when he deals at expensive tables. To test her belief, she observed 500 hands each at the $100- limit table and the
> Medical experts advocate the use of vitamin and mineral supplements to help fight infections. A study undertaken by researchers at Memorial University recruited 96 men and women age 65 and older. One-half of them received daily supplements of vitamins an
> Many small retailers advertise in their neighborhoods by sending out flyers. People deliver these to homes and are paid according to the number of flyers delivered. Each deliverer is given several streets whose homes become their responsibility. One of t
> Approximately 20 million Americans work for themselves. Most run single-person businesses out of their homes. One-quarter of these individuals use personal computers in their businesses. A market research firm, Computer Intelligence InfoCorp, wanted to k
> Most English professors complain that students don’t write very well. In particular they point out that students often confuse quality and quantity. A study at the University of Texas examined this claim. In the study undergraduate students were asked to
> There are currently 121,678 people waiting for lifesaving organ transplants in the United States. Of these, 100,791 await kidney transplants. (as of January 2016). The median wait time for an individual’s first kidney transplant is 3.6 years and can vary
> Personal spending is usually an indicator of the health of the overall economy. An increase tends to indicate that consumers are optimistic; a decrease indicates pessimism. Gallup tracks the spending of a random sample of American adults. The results for
> After observing the results of the test in Exercise 13.211, a statistics practitioner organized another experiment. People were matched according to gender, height, and weight. One member of each matched pair then exercised vigorously twice a week and th
> Most people exercise in order to lose weight. To determine better ways to lose weight, a random sample of male and female exercisers was divided into groups. The first group exercised vigorously twice a week. The second group exercised moderately four ti
> The Program for International Student Assessment (PISA) conducts tests of 15-year-olds. The tests jointly developed by the participating countries are tests for reading literary test, mathematical literacy test, and scientific literary test. Random sampl
> High blood pressure (hypertension) is a leading cause of strokes. Medical researchers are constantly seeking ways to treat patients suffering from this condition. A specialist in hypertension claims that regular aerobic exercise can reduce high blood pre
