Immigration reform has focused on dividing illegal immigrants into two groups: long-term and short-term. In a random sample of 958 construction workers from the Northeast, 66 are illegal short-term immigrants. In the Midwest, 42 out of a sample of 1070 are illegal short-term immigrants. a) Is there evidence that the percentage of construction workers who are illegal short-term immigrants differs in the two regions? b) Give a 90% confidence interval for the difference in proportions.
> How does the cost of a movie depend on its length? Data on the cost (millions of dollars) and the running time (minutes) for major release films in one recent year are summarized in these plots and computer output: a) Explain in words and numbers wh
> The earth has been getting warmer. Most climate scientists agree that one important cause of the warming is the increase in atmospheric levels of carbon dioxide (CO2), a greenhouse gas. Here is part of a regression analysis of the mean annual air tempera
> Several studies have found that the frequency with which shoppers browse Internet retailers is related to the frequency with which they actually purchase products and/or services online. Here are data showing the age of respondents and their answer to th
> For each of the following situations, state whether you’d use a chi-square goodness-of-fit test, a chi-square test of homogeneity, a chi-square test of independence, or some other statistical test. a) Is the quality of a car affected by what day it was
> For each of the following situations, state whether you’d use a chi-square goodness-of-fit test, chi square test of homogeneity, chi-square test of independence, or some other statistical test. a) A brokerage firm wants to see whether the type of accoun
> A marketing executive tested two incentives to see what percentage of customers would enroll in a new Web-based loyalty program. The customers were asked to log on to their accounts on the Web and provide some demographic and spending information. As an
> In 2010, the U.S. Congress passed the historic health care reform bill that will provide some type of coverage for the millions of Americans without health care insurance. Just how widespread is the lack of medical coverage in 2016, years after health ca
> You are on the financial planning team for monitoring a high spending segment of a credit card. You know that customers tend to spend more during December before the holidays, but you’re not sure about the pattern of spending in the months after the holi
> In Chapter 4, we examined the regression of the sales price of a home on its size and saw that larger homes generally fetch a higher price. How much can we learn about a house from the fact that it has a fireplace or more than the average number of bedro
> A philanthropic organization collects and buys data on their donor base. The full database contains about 4.5 million donors and over 400 variables collected (continued) on each, but the dataset Donor profiles is a sample of 916 donors and includes the v
> A real estate agent wants to know how many owners of homes worth over $1,000,000 might be considering putting their home on the market in the next 12 months. He surveys 40 of them and finds that 10 of them are considering such a move. Are all the assumpt
> Using the Paralyzed Veterans dataset, construct a 95% confidence interval for the mean age of a potential donor to the Paralyzed Veterans. Test the hypothesis that the mean age is 62 years old. Discuss what the confidence interval says about the hypothes
> In the last chapter, you looked at the data file Real estate sample 1200, which holds the following variables: • Sale Price (in $) • Lot size (size of the lot in acres) • Waterfront (Yes, No) • Age (in years) • Central Air (Yes, No) • Fuel Type (Wood, Oi
> A real estate agent is trying to understand the pricing of homes in her area, a region comprised of small to midsize towns and a small city. For each of 1200 homes recently sold in the region, the file Real estate sample 1200 holds the following variable
> Utilities must forecast the demand for energy use far into the future because it takes decades to plan and build new power plants. Ron Baker, who worked for New York State Electric and Gas (NYSEG), had the job of predicting the proportion of homes that w
> In 2011, when the Gallup organization polled investors, 34% rated gold the best long-term investment. But in April of 2017 Gallup surveyed a random sample of U.S. adults (news.gallup.com/poll/208820/americans-favor-real-estate-long-terminvestment.aspx).
> Every spring, Nenana, Alaska, hosts a contest in which participants try to guess the exact minute that a wooden tripod placed on the frozen Tanana River will fall through the breaking ice. The contest started in 1917 as a diversion for railroad engineers
> The product manager at a subsidiary of Kraft Foods, Inc., is interested in learning how sensitive sales are to changes in the unit price of a frozen pizza in Dallas, Denver, Baltimore, and Chicago. The product manager has been provided data on both Price
> In Exercise 59, we looked at the times in two different heats for the 800-m men’s run from the 2012 Olympics. Unlike track events, swimming heats are not determined at random. Instead, swimmers are seeded so that better swimmers are pla
> In Olympic running events, preliminary heats are determined by random draw, so we should expect the ability level of runners in the various heats to be about the same, on average. The table gives the times (in seconds) for the 800-m men’
> Here’s some additional information about the pizza sales data presented in Exercise 57. It is generally thought that sales spike during the weeks leading up to AFC and NFC football championship games, as well as leading up to the Super
> The proportion of adult women in the United States is approximately 51%. A marketing survey telephones 400 people at random. a) What is the sampling distribution of the observed proportion that are women? b) What is the standard deviation of that propo
> A national food product company believes that it sells more frozen pizza during the winter months than during the summer months. Average weekly sales for a sample of stores in the Baltimore area over a three-year period provided the following data for sa
> The average credit card debt carried by college students was compared at public versus private universities. It was reported that a significant difference existed between the two types of institutions and that students at private universities carried hig
> The National Assessment in Education Program compared science scores for students who had home Internet access with the scores of those who did not, as shown in the graph. They report that the differences are statistically significant. a) Explain what
> The U.S. Bureau of Economic Analysis provides information on the GDP in the United States by metropolitan area (www.bea.gov). The Bureau recently released figures that showed the percent change in real GDP by metropolitan area for 2004–
> The U.S. Bureau of Economic Analysis also provides information on the growth of the U.S. economy (www.bea.gov). The Bureau recently released figures that they claimed showed a growth spurt in the western region of the United States. Using the table and m
> The U.S. Bureau of Economic Analysis provides information on the Gross Domestic Product Per Capita (GDP PC) in the United States by state (www.bea.gov). The Bureau recently released figures that showed the real (GDP PC) by state for 2016. Using the data
> In a recent study of enterprise resource planning (ERP) system effectiveness, researchers asked companies about how they assessed the success of their ERP systems. Out of 335 manufacturing companies surveyed, they found that 201 used return on investment
> It has become more common for shoppers to “comparison shop” using the Internet. Respondents to a Pew survey in 2013 who owned cell phones were asked whether they had, in the past 30 days, looked up the price of a produ
> The Pew Internet & American Life Project routinely conducts surveys to gauge the impact of the Internet and technology on daily life. A recent survey asked respondents if they read online journals or blogs, an Internet activity of potential interest
> Every year, Fortune magazine lists the 100 best companies to work for, based on criteria such as pay, benefits, days off, and diversity. In 2018, the top three were Sales Force, Wegmans Food Markets, and Ultimate Softeware. In 2017, of the top 30, 10 wer
> The investment website of Exercise 1 draws a random sample of 200 investors from their customers. Suppose that the true proportion of smartphone users is 36%. a) What would the standard deviation of the sampling distribution of the proportion of smartph
> Use the survey results in the table below to investigate differences in employee job satisfaction among organizations in the United States with different management styles. a) Select the appropriate procedure. b) Check the assumptions. c) State the hyp
> Consider only the companies that have outsourced their IT and HR business segments. Do these data suggest significant differences between companies in the financial and industrial goods sectors with regard to their outsourcing decisions? a) Select the
> Many companies have chosen to outsource segments of their business to external providers in order to cut costs and improve quality and/ or efficiencies. Common business segments that are outsourced include Information Technology (IT) and Human Resources
> Find a 95% confidence interval for the difference in the proportion of women who survived and the proportion of men who survived for the data in Exercise 44. (Assume the passengers on the Titanic were representative of others who might have taken the tri
> Find a 95% confidence interval for the difference in the proportions of Black renters in the two sections for the data in Exercise 43.
> Newspaper headlines at the time and traditional wisdom in the succeeding decades have held that women and children escaped the Titanic in greater proportion than men. Here’s a table with the relevant data. Do you think that survival was
> The director of a small business development center located in a mid-sized city is reviewing data about its clients. In particular, she is interested in examining if the distribution of business owners across the various stages of the business life cycle
> In some situations where the expected counts are too small, as in Exercise 36, we can complete an analysis anyway. We can often proceed after combining cells in some way that makes sense and also produces a table in which the conditions are satisfied. He
> A recent report concludes that while Internet users like the convenience of online shopping, they do have concerns about privacy and security (Online Shopping, Washington, DC, Pew Internet & American Life Project, February 2008). A random sample of a
> The proportion of adult women in the United States is approximately 51%. A marketing survey telephones 400 people at random. a) What proportion of women in the sample of 400 would you expect to see? b) How many women, on average, would you expect to fi
> The Cornell National Social Survey8 asked 1000 U.S. adults about their employment status and whether they owned stocks. This table gives the counts of the 938 respondents: Is there a relationship between employment status and stock ownership? a) Select
> A leading CEO mentoring organization offers a program for chief executives, presidents, and business owners with a focus on developing entrepreneurial skills. Women and men executives that recently completed the program rated its value. Are perceptions o
> Pew Research surveyed U.S. adults in December 2011. They asked how important it is “to you personally” to be successful in a high-paying career or profession. Among 18- to 34-year-old respondents, do men and women have
> A full service brokerage firm surveyed a random sample of 1200 clients asking them to indicate the likelihood that they would add inflation-linked annuities and bonds to their portfolios within the next year. The table below shows the distribution of res
> A large company in the northeastern United States that buys fish from local fishermen and distributes them to major companies and restaurants is considering launching a new ad campaign on the health benefits of fish. As evidence, they would like to cite
> In early 2012, the proportion of mortgages that were “under water”—a negative equity position in which the homeowner owes more than the value of the home—was highest in Nevada and Arizona (s.wsj .net/public/resources/documents/info-NEGATIVE_ EQUITY_0911.
> Public libraries are not run for profit, but they must know their customers. A Pew Research survey in November 2012 found that 426 of 584 surveyed parents of young children had current library cards. 967 of 1668 adults without young children had library
> GfK Roper Consulting gathers information on consumer preferences around the world to help companies monitor attitudes about health, food, and health care products. They asked people in many different cultures how they felt about the following statement:
> A recent report suggests that Chief Information Officers (CIOs) who report directly to Chief Financial Officers (CFOs) rather than Chief Executive Officers (CEOs) are more likely to have IT agendas that deal with cost cutting and compliance (SearchCIO.co
> As in Exercise 17, you want to estimate the proportion of traditional college students on your campus who own their own car. However, from some research on other college campuses, you believe the proportion will be near 20%. a) What sample size is neede
> For the regression of Exercise 1, find the standard error of the regression slope. Show all three values that go into the calculation. Exercise 1: A website that rents movies online recorded the age and the number of movies rented during the past month
> A survey of 430 randomly chosen adults finds that 47 of 222 men and 37 of 208 women had purchased books online. a) Is there evidence that the sex of the person and whether they buy books online are associated? b) If your conclusion in fact proves to be
> In March and April of 2011, the Pew Research Center asked 2142 U.S. adults and 1055 college presidents whether they would “rate the job the higher education system is doing in providing value for the money spent by students and their fa
> It’s common folk wisdom that cranberries can help prevent urinary tract infections in women. A leading producer of cranberry juice would like to use this information in their next ad campaign, so they need evidence of this claim. In 2001, the British Med
> Consumer Reports uses surveys given to subscribers of its magazine and website (www.ConsumerReports.org) to measure reliability in automobiles. This annual survey asks about problems that consumers have had with their cars, vans, SUVs, or trucks during t
> Students in an Introductory statistics class at a large university were classified by birth order and by the college they attend. a) What kind of chi-square test is appropriate—goodnessof- fit, homogeneity, or independence? b) State y
> The table shows the rank attained by male and female officers in the New York City Police Department (NYPD). Do these data indicate that men and women are equitably represented at all levels of the department? (All possible ranks in the NYPD are shown.)
> Here is a table showing who survived the sinking of the Titanic based on whether they were crew members or passengers booked in first-, second-, or third-class staterooms. a) If we draw an individual at random from this table, what’s
> Census data for New York City indicate that 29.2% of the under-18 population is white, 28.2% black, 31.5% Latino, 9.1% Asian, and 2% are of other ethnicities. The New York Civil Liberties Union points out that of 26,181 police officers, 64.8% are white,
> For a lottery to be successful, the public must have confidence in its fairness. One of the lotteries in Maryland is Pick-3 Lottery, where 3 random digits are drawn each day.7 A fair game depends on every value (0 to 9) being equally likely at each of th
> A sales representative who is on the road visiting clients thinks that, on average, he drives the same distance each day of the week. He keeps track of his mileage for several weeks and discovers that he averages 122 miles on Mondays, 203 miles on Tuesda
> Suppose you want to estimate the proportion of traditional college students on your campus who own their own car. You have no preconceived idea of what that proportion might be. a) What sample size is needed if you wish to be 95% confident that your esti
> A company advertises that its premium mixture of nuts contains 10% Brazil nuts, 20% cashews, 20% almonds, 10% hazelnuts, and that the rest are peanuts. You buy a large can and separate the various kinds of nuts. Upon weighing them, you find there are 112
> According to recent research (www .nas.org) married couples who met their spouse through an online dating service may have a different divorce rate than those who met “off line.” (“Online Mating” from Proceedings of the National Academy of Sciences of th
> After getting trounced by your little brother in a children’s game, you suspect that the die he gave you is unfair. To check, you roll it 60 times, recording the number of times each face appears. Do these results cast doubt on the die&
> The Chevy Tahoe Hybrid got a lot of attention when it first appeared. It is a relatively high-priced hybrid SUV that makes use of the latest technologies for fuel efficiency. One of the more popular hybrid SUVs on the market is the modestly priced Ford E
> In Exercises 50 and 52, we see the number of advertised brand names people recalled immediately after watching TV shows and 24 hours later. Strangely enough, it appears that they remembered more about the ads the next day. Should we conclude this is true
> In the study described in Exercise 50, the researchers also contacted the subjects again, 24 hours later, and asked them to recall the brands advertised. a) Is there a significant difference in viewers’ abilities to remember brands ad
> You are a consultant to the marketing department of a business preparing to launch an ad campaign for a new product. The company can afford to run ads during one TV show, and has decided not to sponsor a show with sexual content (see Exercise 50). You cr
> The Journal of Applied Psychology reported on a study that examined whether the content of TV shows influenced the ability of viewers to recall brand names of items featured in the commercials. The researchers randomly assigned volunteers to watch one of
> A small appliance company is interested in comparing delivery times of their product during two months. They are concerned that the summer slow-downs in August cause delivery times to lag during this month. Given the following delivery times (in days) of
> When implementing a packaged Enterprise Resource Planning (ERP) system, many companies report that the module they first install is Financial Accounting. Among the measures used to gauge the effectiveness of their ERP system implementation is acceleratio
> As in Exercise 13, from a survey of coworkers you find that 48% of 200 have already received this year’s flu vaccine. An approximate 95% confidence interval is (0.409, 0.551). a) How would the confidence interval change if the sample size had been 800 i
> A company institutes an exercise break for its workers to see if this will improve job satisfaction, as measured by a questionnaire that was given to a random sample of workers to assess their satisfaction. a) Identify the procedure you would use to a
> The Price-to-Book-value ratio is often used by investors to indicate whether a stock’s price is particularly high or low relative to the value of the company. But different market sectors expect different Price/Book values. Here are dat
> In an investigation of environmental causes of disease, data were collected on the annual mortality rate (deaths per 100,000) for males in 61 large towns in England and Wales. In addition, the water hardness was recorded as the calcium concentration (par
> Do the data in Exercise 42 suggest that the American League’s designated hitter rule may lead to more runs per game scored? a) Write the null and alternative hypotheses. b) Find a 95% confidence interval for the difference in mean runs per game, and inte
> A factory hiring people to work on an assembly line gives job applicants a test of manual agility. a) Find 95% confidence intervals for the average number of pegs that males and females can each place. b) Those intervals overlap. What does this suggest
> American League baseball teams play their games with the designated hitter rule, meaning that pitchers do not bat. The league believes that replacing the pitcher, traditionally a weak hitter, with another player in the batting order produces more runs an
> A pharmaceutical company is producing and marketing a ginkgo biloba supplement to enhance memory. In an experiment to test the product, subjects were assigned randomly to take ginkgo biloba supplements or a placebo. Their memory was tested to see whether
> Exercise 39 considered possible changes in the numbers of tropical cyclones that have grown large enough to be officially named. Regardless of the number of storms, has the fraction of named storms that grew to hurricane strength changed? Here are those
> It has been suggested that global climate change may be affecting the frequency of tropical storms. The data here show the number of tropical cyclones (including hurricanes) assigned official names by the National Hurricane Center. Is there evidence of a
> The owner of a small organic food store was concerned about her sales of a specialty yogurt manufactured in Greece. As a result of increasing fuel costs, she recently had to increase its price. To help boost sales, she decided to place the product on a d
> From the survey in Exercise 11, a) How would the confidence interval change if the confidence level had been 90% instead of 95%? b) How would the confidence interval change if the sample size had been 300 instead of 200? (Assume the same sample proport
> A company is producing and marketing new reading activities for elementary school children that it believes will improve reading comprehension scores. A researcher randomly assigns third graders to an eight-week program in which some will use these activ
> The Pew Internet & American Life Project (www.pewinternet.org/) conducts surveys to gauge how the Internet and technology impact daily life of individuals, families, and communities. In a recent survey Pew asked respondents if they thought that compu
> Morningstar (www.morningstar.com) selects mutual funds as “Medalist” funds expected to perform well over the long term. You have decided to invest in a bond fund and plan to limit your choice of funds to Morningstar “medalist” funds. But now you must cho
> Chemical analyses of 1599 red and 4898 white Italian wines revealed the following summary statistics for pH (a measure of acidity): Is there a difference in pH between red and white wines? a) Write the null and alternative hypotheses. b) What condition
> A food company is concerned about recent criticism of the sugar content of their children’s cereals. The data show the sugar content (as a percentage of weight) of several national brands of children’s and adultsâ
> Suppose the specialty food chain from Exercise 26 wants to now compare the change in sales across different regions. An examination of the difference in sales over a 37-week period in a recent year for 8 stores in the state of Massachusetts compared to 1
> A trucking company would like to compare two different routes for efficiency. Truckers are randomly assigned to two different routes. Twenty truckers following Route A report an average of 40 minutes, with a standard deviation of 3 minutes. Twenty trucke
> The accounting firm described in Exercise 28 is interested in providing opportunities for its auditors to gain more expertise in statistical sampling methods. They wish to compare traditional classroom instruction with online self-paced tutorials. Audito
> The study of the new CPMP mathematics methodology described in Exercise 25 also tested students’ abilities to solve word problems. This table shows how the CPMP and traditional groups performed. What do you conclude? (Assume that the as
> An accounting firm is trying to decide between IT training conducted in-house and the use of third party consultants. To get some preliminary cost data, each type of training was implemented at two of the firm’s offices located in diffe
> From the survey in Exercise 11, which of the following are true? If they are not true, explain briefly why not. a) 95% of the 200 students are in the interval (0.283, 0.417). b) The true proportion of students who use laptops to take notes is captured
> During the study described in Exercise 25, students in both CPMP and traditional classes took another algebra test that did not allow them to use calculators. The table shows the results. Are the mean scores of the two groups significantly different? Ass
> A chain that specializes in healthy and organic food would like to compare the sales performance of two of its primary stores in the state of Massachusetts. These stores are both in urban, residential areas with similar demographics. A comparison of the
