On election day, a pollster for Fox News positions herself outside a polling place near her home and asks the first 50 voters leaving the facility to complete a survey.
> List the eight properties of the linear correlation coefficient.
> (a) The correlation between number of married residents and number of unemployed residents for the 50 states and Washington, DC, is 0.922. A scatter diagram of the data is shown. What type of relation appears to exist between number of marriages and numb
> Recessions are defined as two consecutive quarters of reduced national output. One measure to assess the severity of a recession is the rate of unemployment. The table shows the number of employed and unemployed residents of the United States at the peak
> Are you more likely to be satisfied with your automobile purchase when it is new or used? The following data represent the level of satisfaction of the buyer for both new and used cars. (a) How many were extremely satisfied with their automobile purchase
> In sports betting, Las Vegas sports books establish winning margins for a team that is favored to win a game. An individual can place a wager on the game and will win if the team bet upon wins after accounting for the spread. For example, if Team A is fa
> On October 6, 2010, Roy Halladay of the Philadelphia Phillies threw the second post-season no-hitter in Major League history. The side-by-side boxplot shows the pitch speed (in miles per hour) for all of Halladay’s pitches during the game. (a) Which pitc
> According to the National Center for Health Statistics, the mean weight of a 20- to 29-year-old female is 156.5 pounds, with a standard deviation of 51.2 pounds. The mean weight of a 20- to 29-year-old male is 183.4 pounds, with a standard deviation of 4
> Michael has just completed his first semester in college. He earned an A in his five-hour calculus course, a B in his four-hour chemistry course, an A in his three-hour speech course, and a C in his three-hour psychology course. Assuming an A equals 4 po
> The frequency distribution listed in the table represents the travel time to work (in minutes) for a random sample of 895 U.S. adults. (a) Approximate the mean travel time to work for U.S. adults. (b) Approximate the standard deviation travel time to wor
> Discuss a possible advantage of offering rewards or incentives to increase response rates. Are there any disadvantages?
> Volume of water lost each day through a leaky faucet
> Suppose that a certain brand of light bulb has a mean life of 600 hours and a standard deviation of 53 hours. (a) A histogram of the data indicates the sample data follow a bell-shaped distribution. According to the Empirical Rule, 99.7% of light bulbs h
> As part of a statistics project, a student surveys 30 randomly selected students and asks them how many speeding tickets they have been issued in the past month. The results of the survey are as follows: (a) Draw a frequency histogram of the data and des
> The following data represent the ages of chief justices of the U.S. Supreme Court when they were appointed. (a) Determine the population mean, median, and mode ages. (b) Determine the range and population standard deviation ages. (c) Obtain two simple ra
> The following data represent the sales price (in dollars) for nine 2-year-old Chevrolet Cobalts in the Los Angeles area. (a) Determine the sample mean and median price. (b) Determine the range, sample standard deviation, and interquartile range. (c) Redo
> One method of estimating body fat is through skinfold thickness measurement using from three to nine different standard anatomical sites around the body from the right side only (for consistency). The tester pinches the skin at the appropriate site to ra
> According to the National Center for Health Statistics, a 19-year-old female whose height is 67.1 inches has a height that is at the 85th percentile. Explain what this means.
> Ever wonder how many words are in a typical inaugural address? The data in the next column represent the lengths of all the inaugural addresses (measured in word count) for all presidents up to Donald Trump. (a) Determine the mean and median number of wo
> The following data represent the muzzle velocity (in meters per second) of rounds fired from a 155-mm gun. Source: Christenson, Ronald, and Blackwood, Larry, “Tests for Precision and Accuracy of Multiple Measuring Devices,” Technometrics, 35(4): 411–421,
> Inflation The side-by-side bar graph to the right shows the average grade point average for the academic years beginning in 1983, 1988, 1993, 1998, 2003, 2008, and 2013, for colleges and universities. (a) Does the graph suggest that grade inflation is a
> The data on the following page represent the average number of hours per week that a random sample of 40 college students spend online. The data are based on the ECAR Study of Undergraduate Students and Information Technology. Construct a stem-and-leaf d
> Suppose a survey asks, “How many hours do you study?” Explain how this could be interpreted in more than one way. Suggest a way in which the question could be improved.
> The following data represent the diameter (in inches) of a random sample of 34 Keebler Chips Deluxe™ Chocolate Chip Cookies. (a) Construct a frequency distribution. (b) Construct a relative frequency distribution. (c) Construct a frequency histogram. Des
> The table shows the home ownership rate in each of the 50 states and Washington, DC, in 2017. Note: The state with the highest home ownership rate is West Virginia and the lowest is Washington, DC. With a lower class limit of the first class of 45 and a
> A random sample of 60 couples married for seven years were asked to give the number of children they have. The results of the survey are as follows: (a) Construct a frequency distribution of the data. (b) Construct a relative frequency distribution of th
> One hundred randomly selected registered voters in the city of Naperville were asked their political affiliation: Democrat (D), Republican (R), or Independent (I). The results of the survey are shown below. (a) Construct a frequency distribution of the d
> The frequency distribution on the following page represents the number of live births (in thousands) in the United States in 2016 by age of mother. (a) Construct a relative frequency distribution. (b) Construct a frequency histogram. Describe the shape o
> The following frequency distribution represents the cause of death in homicides for a random sample of homicides. (a) Construct a relative frequency distribution. (b) Construct a relative frequency bar graph. (c) Construct a pie chart.
> The graphic to the right is a USA Today—type graph displaying women’s preference for shoes. (a) Which type of shoe is preferred the most? The least? (b) How is the graph misleading?
> In 2017, the average earnings of a high school graduate were $30,624. At $52,484, the average earnings of a recipient of a bachelor’s degree were about 71% higher. Source: U.S. Census Bureau. (a) Construct a misleading graph that a college recruiter migh
> The following data represent the percentage of total adjusted gross income (AGI) earned and percentage of tax paid by various income classes. The top 1% represents the percentage of total AGI earned and tax paid by those whose income is higher than 99% o
> Harris Interactive conducted a poll of U.S. adults and asked, “When there is a voiceover in a commercial, which type of voice is more likely to sell me a car?” Results of the survey are in the bar graph. (a) How many participants were in the survey? (b)
> Discuss why the order of questions or choices within a questionnaire are important in sample surveys.
> What is the role of randomization in a designed experiment? If you were conducting a completely randomized design with four treatments and 100 experimental units, describe how you would randomly assign the experimental units to the treatments.
> Many newspaper articles discuss the dangers of teens texting while driving. Suppose you are a journalist and want to chime in on the discussion. However, you want your article to be more compelling, so you decide to conduct an experiment with one hundred
> Go to an online science magazine such as Science Daily (www.sciencedaily.com) or an open source online medical journal such as BioMed Central (www.biomedcentral.com) and identify an article that includes statistical research. (a) Was the study you select
> Describe what is meant by a matched-pairs design. Contrast this experimental design with a completely randomized design.
> A marketing research firm wants to know whether information presented in a commercial is better recalled when presented using humor or serious commentary by adults between 18 and 35 years of age. They will use an exam that asks questions of 50 subjects a
> A common tip for taking multiple-choice tests is to always pick (b) or (c) if you are unsure. The idea is that instructors tend to feel the answer is more hidden if it is surrounded by distractor answers. An astute statistics instructor is aware of this
> Researchers wanted to assess the effect of low alcohol consumption on reaction time in seniors, believing that even low levels of alcohol consumption can impair the ability to walk, thereby increasing the likelihood of falling. They identified 13 healthy
> Smoking and drinking coffee have a tendency to stain teeth. In an effort to determine the ability of chewing gum to remove stains on teeth, researchers conducted an experiment in which 64 bovine incisors (teeth) were stained with natural pigments such as
> Based on the Military Standard 105E (ANS1/ASQC Z1.4, ISO 2859) Tables, a lot of 91 to 150 items with an acceptable quality level (AQL) of 1% and a normal inspection plan would require a sample of size 13 to be inspected for defects. If the sample contain
> A quality-control engineer wants to be sure that bolts coming off an assembly line are within prescribed tolerances. He wants to conduct a systematic sample by selecting every 9th bolt to come off the assembly line. The machine produces 30,000 bolts per
> Why is a high response rate desired? How would a low response rate affect survey results?
> The mayor of a town wants to conduct personal interviews with small business owners to determine if there is anything he could do to help improve business conditions. The following list gives the names of the companies in the town. Obtain a simple random
> Each of the following surveys has bias. Determine the type of bias and suggest a remedy. (a) A politician sends a survey about tax issues to a random sample of subscribers to a literary magazine. (b) An interviewer with little foreign language knowledge
> Officers for the Department of Motor Vehicles pull aside every 40th tractor trailer passing through a weigh station, starting with the 12th, for an emissions test.
> Thirty-five sophomores, 22 juniors, and 35 seniors are randomly selected to participate in a study from 574 sophomores, 462 juniors, and 532 seniors at a certain high school.
> An Internet service provider randomly selects 15 residential blocks from a large city and surveys every household in these 15 blocks to determine the number that would use a high-speed Internet service.
> Read the following description of an observational study and determine whether it is a cross-sectional, a case-control, or a cohort study. Explain your choice. The Cancer Prevention Study II (CPS-II) examines the relationship among environmental and life
> A sample of 504 patients in early stages of Alzheimer’s disease is divided into two groups. One group receives an experimental drug; the other receives a placebo. The advance of the disease in the patients from the two groups is tracked at 1-month interv
> A parent group examines 25 randomly selected PG-13 movies and 25 randomly selected PG movies, records the number of sexual innuendos and curse words that occur in each, and then compares the number of sexual innuendos and curse words between the two movi
> Number of siblings
> Discuss the pros and cons of telephone interviews that take place during dinner time in the early evening.
> Stock rating (strong buy, buy, hold, sell, strong sell)
> Marital status
> Birth year
> In the 2019 NCAA Football Championship Game, quarterback Trevor Lawrence completed 62.5% of his passes for a total of 347 yards.
> In a survey of 1011 people age 50 or older, 73% agreed with the statement “I believe in life after death.” Source: Bill Newcott. “Is There Life after Death?,” AARP Magazine, Sept./Oct. 2007.
> Brand name of a pair of running shoes
> Weight in carats of an uncut diamond
> Number of new automobiles sold at a dealership on a given day
> Explain the steps in designing an experiment.
> Use the results of Problem 11 from Section 12.3 to answer the following questions: (a) Predict the mean well-being index composite score of all individuals whose commute time is 20 minutes. (b) Construct a 90% confidence interval for the mean well- being
> What are the advantages of having a presurvey when constructing a questionnaire that has closed questions?
> Using the sample data from Problem 8 in Section 12.3, (a) Predict the mean value of y if x = 1.8. (b) Construct a 95% confidence interval for the mean value of y if x = 1.8. (c) Predict the value of y if x = 1.8. (d) Construct a 95% prediction interval f
> Using the sample data from Problem 7 in Section 12.3, (a) Predict the mean value of y if x = 1.4. (b) Construct a 95% confidence interval for the mean value of y if x = 1.4. (c) Predict the value of y if x = 1.4. (d) Construct a 95% prediction interval f
> Using the sample data from Problem 6 in Section 12.3, (a) Predict the mean value of y if x = 8. (b) Construct a 95% confidence interval for the mean value of y if x = 8. (c) Predict the value of y if x = 8. (d) Construct a 95% prediction interval for the
> Using the sample data from Problem 5 in Section 12.3, (a) Predict the mean value of y if x = 7. (b) Construct a 95% confidence interval for the mean value of y if x = 7. (c) Predict the value of y if x = 7. (d) Construct a 95% prediction interval for the
> Intervals constructed about the predicted value of y, at a given level of x, that are used to measure the accuracy of a single individual’s prediction are called ____ intervals for a(n)____ response.
> Intervals constructed about the predicted value of y, at a given level of x, that are used to measure the accuracy of the mean response of all individuals in the population are called_____ intervals for a(n) ______ response.
> Can a photograph of an individual be used to predict their intelligence? Researchers at Charles University in Prague, Czech Republic, had 160 raters analyze the photos of 80 students and asked each rater to rate the intelligence and attractiveness of the
> The following data represent the speed at which a ball was hit (in miles per hour) and the distance it traveled (in feet) for a random sample of home runs in a Major League baseball game in 2018. (a) Treating speed at which the ball was hit as the explan
> Is the width of a tornado related to the distance for which the tornado is on the ground? Go to www.pearsonhighered.com/sullivanstats to obtain the data file 12_4_17. These data represent the width (in yards) and length (in miles) for tornadoes in Louisi
> Using the results of Problem 20 from Section 12.3, explain why it does not make sense to construct confidence or prediction intervals based on the least-squares regression equation.
> Discuss the benefits of having trained interviewers.
> Using the results of Problem 19 from Section 12.3, explain why it does not make sense to construct confidence or prediction intervals based on the least-squares regression equation.
> American Black Bears Use the results of Problem 18 from Section 12.3 to answer the following questions: (a) Predict the mean weight of American black bears with a total length of 154.5 cm. (b) Construct a 95% confidence interval for the mean weight of Am
> Use the results of Problem 17 in Section 12.3 to answer the following questions: (a) Predict the mean annual ROI of all four-year schools whose cost is $180,000. (b) Construct a 95% confidence interval for the mean annual ROI found in part (a). (c) Predi
> Tar and Nicotine Use the results of Problem 16 in Section 12.3 to answer the following questions: (a) Predict the mean nicotine content of all cigarettes whose tar content is 12 mg. (b) Construct a 95% confidence interval for the tar content found in par
> Use the results of Problem 15 from Section 12.3 to answer the following questions: (a) Predict the mean 28-day strength of concrete whose 7-day strength is 2550 psi. (b) Construct a 95% confidence interval for the mean 28-day strength of concrete whose 7
> Use the results of Problem 14 in Section 12.3 to answer the following questions: (a) Predict the mean wind speed of all hurricanes whose atmospheric pressure is 950 mb. (b) Construct a 95% confidence interval for the mean wind speed found in part (a). (c
> Use the results of Problem 13 from Section 12.3 to answer the following questions: (a) Predict the mean head circumference of children who are 25.75 inches tall. (b) Construct a 95% confidence interval for the mean head circumference of children who are
> Use the results of Problem 12 from Section 12.3 to answer the following questions: (a) Predict the mean interest rate of all individuals whose credit score is 730. (b) Construct a 90% confidence interval for the mean interest rate of all individuals whos
> If /is not rejected, what is the best estimate for the value of the response variable for any value of the explanatory variable?
> In the least-squares regression model, / / is a random error term with mean_____ and standard deviation /
> What are some solutions to nonresponse?
> True or False: In a least-squares regression, the response variable is normally distributed with mean / and standard deviation .
> Suppose a least-squares regression line is given by / = 4.302x - 3.293. What is the mean value of the response variable if x = 20?
> Why don’t we conduct inference on the linear correlation coefficient?
> Why is it desirable to have the explanatory variables spread out to test a hypothesis regarding 1 or to construct confidence intervals about 1?
> What do the y-coordinates on the least-squares regression line represent?
> Why is it important to perform graphical as well as analytical analyses when analyzing relations between two quantitative variables?
> Zillow.com is a site that can be used to assess the value of homes in your neighborhood. The organization provides a list of homes for sale as well as a Zestimate, which is the price Zillow believes the home will sell for. The following data represent th
> The output shown was obtained from Minitab. (a) The least-squares regression equation is / = 1.3962x + 12.396. What is the predicted value of y at x = 10? (b) What is the mean of y at x = 10? (c) The standard error, se, is 2.167. What is an estimate of
> A doctor wanted to determine whether there is a relation between a male’s age and his HDL (so-called good) cholesterol. He randomly selected 17 of his patients and determined their HDL levels. He obtained the following data. (a) Draw a scatter diagram of
> A bear market is a market condition in which the price of the security falls. A bear market in the stock market is defined as a condition in which the market declines by 20% or more over the course of at least two months. The following data represent the
> Why is it rare for frames to be completely accurate?
> The following data represent the total compensation for 12 randomly selected chief executive officers (CEOs) and the company’s stock performance in 2017. (a) Treating compensation as the explanatory variable, x, determine the estimates of / (b) Assuming
> In 1969, Dr. Michael R. Pelton of the University of Tennessee initiated a long-term study of the American black bear (Ursus americanus) population in Great Smoky Mountains National Park. One aspect of the study was to develop a model that could be used t
