Question: The U.S. Census Bureau tracks the
The U.S. Census Bureau tracks the median price for new home sales by month of year. The median prices for April for 22 years follow (U.S. Census Bureau website).
a. Construct a time series plot. Comment on any pattern you observe. Discuss some of the factors that may have resulted in this time series plot.
b. Given the time series plot in part (a), do you think the forecasting methods developed in this section are appropriate for this time series? Explain.
c. To forecast a value for Year 23, how much of the past data would you use? Explain.
> The gap between the earnings of men and women with equal education is narrowing but has not closed. Sample data for seven men and seven women with bachelor’s degrees are as follows. Data are shown in thousands of dollars. Men ……………………………….. Women 35.6 …
> Ten individuals participated in a taste test involving two brands of a product. Sample results show 7 preferred brand A, 2 preferred brand B, and 1 was unable to state a preference. With α = .05, test for a significant difference in the preferences for t
> Samples of starting annual salaries for individuals entering the public accounting and financial planning professions follow. Annual salaries are shown in thousands of dollars. a. Use a .05 level of significance and test the hypothesis that there is no d
> Two fuel additives are being tested to determine their effect on gasoline mileage. Seven cars were tested with additive 1 and nine cars were tested with additive 2. The following data show the miles per gallon obtained with the two additives. Use α = .05
> The Scholastic Aptitude Test (SAT) consists of three parts: critical reading, mathematics, and writing. Each part of the test is scored on a 200- to 800-point scale with a median of approximately 500. Scores for each part of the test can be assumed to be
> The Ladies Professional Golf Association (LPGA) ANA Inspiration tournament was held in April 2015 at the Mission Hills Country Club in Rancho Mirage, California. Shown here are first-round and second-round scores for a random sample of 13 golfers. Use &I
> A test was conducted for two overnight mail delivery services. Two samples of identical deliveries were set up so that both delivery services were notified of the need for a delivery at the same time. The hours required to make each delivery follow. Do t
> Percents of on-time arrivals for flights in the past two years were collected for 11 randomly selected airports. Data for these airports follow. Use α = .05 to test the hypothesis that there is no difference between the median percent of on
> A sample of 10 men was used in a study to test the effects of a relaxant on the time required to fall asleep. Data for 10 subjects showing the number of minutes required to fall asleep with and without the relaxant follow. Use a .05 level of significance
> Two fuel additives are tested to determine their effect on miles per gallon for passenger cars. Test results for 12 cars follow; each car was tested with both fuel additives. Use α = .05 and the Wilcoxon signed-rank test to see whether ther
> Young Adult magazine states the following hypotheses about the mean age of its subscribers. H0: µ = 28 Ha: µ ≠ 28 a. What would it mean to make a Type II error in this situation? b. The population standard deviation is assumed known at σ = 6 years and th
> Competition in the personal computer market is intense. A sample of 450 purchases showed 202 Brand A computers, 175 Brand B computers, and 73 other computers. Use a .05 level of significance to test the null hypothesis that Brand A and Brand B have the s
> Nielsen Media Research identified The Big Bang Theory and This is Us as the two top-rated prime-time television series. In a local television preference survey, 750 individuals were asked to indicate their favorite prime-time television series: Three hun
> The following hypothesis test is to be conducted. H0: Median ≤ 150 Ha: Median > 150 A sample of 30 provided 22 observations greater than 150, 3 observations equal to 150, and 5 observations less than 150. Use α = .01. What is your conclusion?
> With the gasoline time series data from Table 17.1, show the exponential smoothing forecasts using α = .1. a. Applying the MSE measure of forecast accuracy, would you prefer a smoothing constant of α = .1 or α =
> Refer again to the gasoline sales time series data in Table 17.1. a. Using a weight of 1/2 for the most recent observation, 1/3 for the second most recent observation, and 1/6 for third most recent observation, compute a three-week weighted moving averag
> Refer to the gasoline sales time series data in Table 17.1. a. Compute four-week and five-week moving averages for the time series. b. Compute the MSE for the four-week and five-week moving average forecasts. c. What appears to be the best number of week
> Consider the following time series data. Construct a time series plot. What type of pattern exists in the data? a. Develop the three-week moving average forecasts for this time series. Compute MSE and a forecast for week 8. b. Use α = .2
> Consider the following time series data. a. Construct a time series plot. What type of pattern exists in the data? b. Develop the three-week moving average forecasts for this time series. Compute MSE and a forecast for week 7. c. Use α =
> Electric power consumption is measured in kilowatt-hours (kWh). The local utility company offers an interrupt program whereby commercial customers that participate receive favorable rates but must agree to cut back consumption if the utility requests the
> Consider the following time series data. a. Compute MSE using the most recent value as the forecast for the next period. What is the forecast for month 8? b. Compute MSE using the average of all the data available as the forecast for the next period. W
> A consumer research group is interested in testing an automobile manufacturer’s claim that a new economy model will travel at least 25 miles per gallon of gasoline (H0: µ ≥ 25). a. With a .02 level of significance and a sample of 30 cars, what is the rej
> Air pollution control specialists in southern California monitor the amount of ozone, carbon dioxide, and nitrogen dioxide in the air on an hourly basis. The hourly time series data exhibit seasonality, with the levels of pollutants showing patterns over
> Three years of monthly lawn-maintenance expenses ($) for a six-unit apartment house in southern Florida follow. a. Construct a time series plot. What type of pattern exists in the data? b. Identify the monthly seasonal indexes for the three years of la
> The quarterly sales data (number of copies sold) for a college textbook over the past three years follow. a. Construct a time series plot. What type of pattern exists in the data? b. Show the four-quarter and centered moving average values for this tim
> Refer to exercise 35. a. Deseasonalize the time series using the adjusted seasonal indexes computed in part (c) of exercise 35. b. Using statistical software, compute the linear trend regression equation for the deseasonalized data. c. Compute the deseas
> Consider the following time series data. a. Construct a time series plot. What type of pattern exists in the data? b. Show the four-quarter and centered moving average values for this time series. c. Compute seasonal indexes and adjusted seasonal index
> Three years of monthly lawn-maintenance expenses ($) for a six-unit apartment house in southern Florida follow. a. Construct a time series plot. What type of pattern exists in the data? b. Develop an estimated regression equation that can be used to ac
> Electric power consumption is measured in kilowatt-hours (kWh). The local utility company offers an interrupt program whereby commercial customers that participate receive favorable rates but must agree to cut back consumption if the utility requests the
> South Shore Construction builds permanent docks and seawalls along the southern shore of Long Island, New York. Although the firm has been in business only five years, revenue has increased from $308,000 in the first year of operation to $1,084,000 in th
> Air pollution control specialists in southern California monitor the amount of ozone, carbon dioxide, and nitrogen dioxide in the air on an hourly basis. The hourly time series data exhibit seasonality, with the levels of pollutants showing patterns that
> The quarterly sales data (number of copies sold) for a college textbook over the past three years follow. a. Construct a time series plot. What type of pattern exists in the data? b. Use the following dummy variables to develop an estimated regression
> Fowle Marketing Research, Inc., bases charges to a client on the assumption that telephone surveys can be completed within 15 minutes or less. If more time is required, a premium rate is charged. With a sample of 35 surveys, a population standard deviati
> Exercises 1 and 2 used different forecasting methods. Which method appears to provide the more accurate forecasts for the historical data? Explain. Exercise 2: Refer to the time series data in exercise 1. Using the average of all the historical data as
> Consider the following time series data. Whenever a categorical variable such as season has k levels, k 2 1 dummy variables are required. a. Construct a time series plot. What type of pattern exists in the data? b. Use the following dummy variables to
> Consider the following time series. a. Construct a time series plot. What type of pattern exists in the data? b. Use the following dummy variables to develop an estimated regression equation to account for seasonal effects in the data: Qtr1 = 1 if Quar
> The following data show Google revenue from 2008 (period 1) to 2017 (period 10) in billions of dollars (Alphabet, Inc. annual reports). These data are in the file GoogleRevenue. a. Construct a time-series plot. What type of pattern exists? b. Develop a
> Giovanni Food Products produces and sells frozen pizzas to public schools throughout the eastern United States. Using a very aggressive marketing strategy they have been able to increase their annual revenue by approximately $10 million over the past 10
> The following data show the number of Netflix subscribers worldwide for the years 2012 (period 1) to 2017 (period 6) (datawrapper website). The data are in the file NetflixSubscribers. a. Construct a time-series plot. What type of pattern exists in the
> The following data shows the average interest rate (%) for a 30-year fixed-rate mortgage over a ten-year period (FreddieMac website). Period ………………………………………………………………. Interest Rate (%) 1 …………………………………………………………………………………………. 6.41 2 ……………………………………………………………
> Skechers is a performance footwear company headquartered in Manhattan Beach, California. The sales for Skechers (in billions of dollars) for 2012 (period 1) to 2017 (period 6) are in the file SkechersSales (annualreports.com). a. Construct a time-series
> The Seneca Children’s Fund (SCF) is a local charity that runs a summer camp for disadvantaged children. The fund’s board of directors has been working very hard in recent years to decrease the amount of overhead expens
> The general fund revenue receipts for the state of Kentucky for 2003 (period 1) to 2017 (period 15) are in the file KYRevenue (ky.gov website). a. Construct a time-series plot. What type of pattern exists in the data? b. Develop a linear trend equation
> In 2017, ABC News reported that 58% of U.S. drivers admit to speeding. Suppose that a new satellite technology can instantly measure the speed of any vehicle on a U.S. road and determine whether the vehicle is speeding, and this satellite technology was
> Consider the following time series. a. Construct a time series plot. What type of pattern exists in the data? b. Using statistical software, develop the quadratic trend equation for the time series. c. What is the forecast for t = 8?
> Refer to the time series data in exercise 1. Using the average of all the historical data as a forecast for the next period, compute the following measures of forecast accuracy. a. Mean absolute error. b. Mean squared error. c. Mean absolute percentage e
> Consider the following time series. a. Construct a time series plot. What type of pattern exists in the data? b. Develop the linear trend equation for this time series. c. What is the forecast for t = 8?
> Consider the following time series data. a. Construct a time series plot. What type of pattern exists in the data? b. Develop the linear trend equation for this time series. c. What is the forecast for t = 8?
> Consider the following time series data. a. Construct a time series plot. What type of pattern exists in the data? b. Develop the linear trend equation for this time series. c. What is the forecast for t = 6?
> Ten weeks of data on the Commodity Futures Index are 7.35, 7.40, 7.55, 7.56, 7.60, 7.52, 7.52, 7.70, 7.62, and 7.55. a. Construct a time series plot. What type of pattern exists in the data? b. Compute the exponential smoothing forecasts for α = .2. c. C
> The following time series shows the sales of a particular product over the past 12 months. a. Construct a time series plot. What type of pattern exists in the data? b. Use α = .3 to compute the exponential smoothing forecasts for the time
> The values of Alabama building contracts (in $ millions) for a 12-month period follow. 240 350 230 260 280 320 220 310 240 310 240 230 a. Construct a time series plot. What type of pattern exists in the data? b. Compare the three-month moving average app
> Corporate triple-A bond interest rates for 12 consecutive months follow. 9.5 9.3 9.4 9.6 9.8 9.7 9.8 10.5 9.9 9.7 9.6 9.6 a. Construct a time series plot. What type of pattern exists in the data? b. Develop three-month and four-month moving averages for
> Internet users were recently asked online to rate their satisfaction with the web browser they use most frequently. Of 102,519 respondents, 65,120 indicated they were very satisfied with the web browser they use most frequently. a. What is the sample pro
> For the Hawkins Company, the monthly percentages of all shipments received on time over the past 12 months are 80, 82, 84, 83, 83, 84, 85, 84, 82, 83, 84, and 83. a. Construct a time series plot. What type of pattern exists in the data? b. Compare the th
> With a smoothing constant of α = .2, equation (17.2) shows that the forecast for week 13 of the gasoline sales data from Table 17.1 is given by F13 = .2Y12 + .8F12. However, the forecast for week 12 is given by F12 = .2Y11 + .8F11. Thus, we could combine
> Consider the following time series data. Using the naive method (most recent value) as the forecast for the next week, compute the following measures of forecast accuracy. a. Mean absolute error. b. Mean squared error. c. Mean absolute percentage error
> As of September 4, 2016, the film Suicide Squad had an average rating of 3.7 out of 5 based on 117,323 viewer ratings (Rotten Tomatoes website). How are the viewer ratings of Suicide Squad related to the viewer age and the viewer ratings of The Secret Li
> Corvette, Ferrari, and Jaguar produced a variety of classic cars that continue to increase in value. The following data, based upon the Martin Rating System for Collectible Cars, show the rarity rating (1–20) and the high price ($1000)
> Home Depot, a home-improvement retailer, sells several brands of washing machines. The following table contains a sample of 24 models of full-size washing machines sold by Home Depot in 2016, with each observation recording the washing machine capacity (
> A study of emergency service facilities investigated the relationship between the number of facilities and the average distance traveled to provide the emergency service. The following table gives the data collected. Number of Facilities …………….. Average
> In working further with the problem of exercise 4, statisticians suggested the use of the following curvilinear estimated regression equation. ŷ = b0 + b1x + b2x2 a. Use the data of exercise 4 to estimate the parameters of this estimated regression equa
> A highway department is studying the relationship between traffic flow and speed. The following model has been hypothesized. y = β 0 + β1x + ε where y = traffic flow in vehicles per hour x = vehicle speed in miles per hour The following data were collect
> Consider the following data for two variables, x and y. a. Does there appear to be a linear relationship between x and y? Explain. b. Develop the estimated regression equation relating x and y. c. Plot the standardized residuals versus yÌ
> According to the Census Bureau, 2,475,780 people are employed by the federal government in the United States as of 2018. Suppose that a random sample of 3,500 of these federal employees was selected and the number of sick hours each of these employees to
> Refer to the Cravens data set in Table 16.5. In Section 16.3 we showed that the estimated regression equation involving Accounts, AdvExp, Poten, and Share had an adjusted coefficient of determination of 88.1%. Use the .05 level of significance and apply
> The following data show the daily closing prices (in dollars per share) for a stock. Date ……………………… Price ($) Nov. 3 ……………………….. 82.87 Nov. 4 ………………………. 83.00 Nov. 7 ……………………….. 83.61 Nov. 8 ……………………….. 83.15 Nov. 9 ……………………….. 82.84 Nov. 10 ………………………..
> Mbuy is a media consulting firm that provides advice to companies on how to allocate their advertising budgets. Mbuy designed a factorial experiment to test the effect of the size of a banner ad on a website and the ad design on the number (in thousands)
> An automobile dealer conducted a test to determine whether the time needed to complete a minor engine tune-up depends on whether a computerized engine analyzer or an electronic analyzer is used. Because tune-up time varies among compact, intermediate, an
> Four different paints are advertised as having the same drying time. To check the manufacturers’ claims, five samples were tested for each of the paints. The time in minutes until the paint was dry enough for a second coat to be applied
> The Jacobs Chemical Company wants to estimate the mean time (minutes) required to process a batch of material on mixer machines produced by three different manufacturers. To limit the cost of testing, four batches of material were mixed on machines produ
> Write a multiple regression equation that can be used to analyze the data for a two-factorial design with two levels for factor A and three levels for factor B. Define all variables.
> Write a multiple regression equation that can be used to analyze the data for a randomized block design involving three treatments and two blocks. Define all variables.
> Consider a completely randomized design involving four treatments: A, B, C, and D. Write a multiple regression equation that can be used to analyze these data. Define all variables.
> Consider the following data for two variables, x and y. a. Develop an estimated regression equation for the data of the form ŷ = β0 + β1x. Comment on the adequacy of this equation for predicting y. b. Develop an
> Suppose a sample of 10,001 erroneous Federal income tax returns from last year has been taken and is provided in the file FedTaxErrors. A positive value indicates the taxpayer underpaid and a negative value indicates that the taxpayer overpaid. a. What i
> Refer to exercise 14. Using age, blood pressure, whether a person is a smoker, and any interaction involving those variables, develop an estimated regression equation that can be used to predict risk. Briefly describe the process you used to develop an e
> Jeff Sagarin has been providing sports ratings for USA Today since 1985. In baseball his predicted RPG (runs per game) statistic takes into account the entire player’s offensive statistics, and is claimed to be the best measure of a pla
> The Ladies Professional Golfers Association (LPGA) maintains statistics on performance and earnings for members of the LPGA Tour. Year-end performance statistics for 134 golfers for 2014 appear in the file LPGA2014Stats (LPGA website). Earnings is the to
> A study provided data on variables that may be related to the number of weeks a person has been jobless. The dependent variable in the study (Weeks) was defined as the number of weeks a person has been jobless due to a layoff. The following independent v
> In 2016, the average monthly residential natural gas bill for Black Hills Energy customers in Cheyenne, Wyoming, is $67.95 (Wyoming Public Service Commission website). How is the monthly average gas bill for a Cheyenne home related to the square footage,
> A 10-year study conducted by the American Heart Association provided data on how age, blood pressure, and smoking relate to the risk of strokes. Data from a portion of this study follow. Risk is interpreted as the probability (times 100) that a person wi
> Refer to the description in exercise 12. a. Develop an estimated regression equation that can be used to predict the total earnings for all events given the average number of putts taken on greens hit in regulation. b. Develop an estimated regression equ
> Predicting LPGA Player’s Average Score. The Ladies Professional Golfers Association (LPGA) maintains statistics on performance and earnings for members of the LPGA Tour. Year-end performance statistics for 134 golfers for 2014 appear in the file LPGA2014
> In a regression analysis involving 30 observations, the following estimated regression equation was obtained: ŷ = 17.6 + 3.8x1 - 2.3x2 + 7.6x3 + 2.7x4 For this estimated regression equation SST = 1805 and SSR = 1760. a. At α = .05, test the significance
> In a regression analysis involving 27 observations, the following estimated regression equation was developed: ŷ = 25.2 + 5.5x1 For this estimated regression equation SST = 1550 and SSE = 520. a. At α = .05, test whether x1 is significant. Suppose that
> The Pew Research Center Internet Project, conducted in 2014 on the 25th anniversary of the Internet, involved a survey of 857 Internet users. It provided a variety of statistics on Internet users. For instance, in 2014, 87% of American adults were Intern
> Consider the following data for two variables, x and y. a. Develop an estimated regression equation for the data of the form ŷ = β0 + β1x. b. Use the results from part (a) to test for a significant relationship be
> Spring is a peak time for selling houses. The file SpringHouses contains the selling price, number of bathrooms, square footage, and number of bedrooms of 26 homes sold in Ft. Thomas, Kentucky, in spring 2018 (realtor.com website). a. Develop scatter plo
> The Condé Nast Traveler Gold List provides ratings for the top 20 small cruise ships. The data shown below are the scores each ship received based upon the results from Condé Nast Traveler’s annual Readers&acir
> PC Magazine provided ratings for several characteristics of computer monitors, including an overall rating (PC Magazine website). The following data show the rating for contrast ratio, resolution, and the overall rating for ten monitors tested using a 0&
> The National Football League (NFL) records a variety of performance data for individuals and teams. To investigate the importance of passing on the percentage of games won by a team, the following data show the conference (Conf), average number of passin
> The owner of Showtime Movie Theaters, Inc., would like to predict weekly gross revenue as a function of advertising expenditures. Historical data for a sample of eight weeks follow. a. Develop an estimated regression equation with the amount of televis
> The Tire Rack maintains an independent consumer survey to help drivers help each other by sharing their long-term tire experiences. The data contained in the file named TireRatings show survey results for 68 all-season tires. Performance traits are rated
> Over the past few years the percentage of students who leave Lakeland College at the end of the first year has increased. Last year Lakeland started a voluntary one-week orientation program to help first-year students adjust to campus life. If Lakeland i
> Community Bank would like to increase the number of customers who use payroll direct deposit. Management is considering a new sales campaign that will require each branch manager to call each customer who does not currently use payroll direct deposit. As
> In Table 15.12 we provided estimates of the probability of using the coupon in the Simmons Stores catalog promotion. A different value is obtained for each combination of values for the independent variables. a. Compute the odds in favor of using the cou
> A poll for the presidential campaign sampled 491 potential voters in June. A primary purpose of the poll was to obtain an estimate of the proportion of potential voters who favored each candidate. Assume a planning value of p* = .50 and a 95% confidence
> Refer to the Simmons Stores example introduced in this section. The dependent variable is coded as y = 1 if the customer used the coupon and 0 if not. Suppose that the only information available to help predict whether the customer will use the coupon is
> The Ladies Professional Golfers Association (LPGA) maintains statistics on performance and earnings for members of the LPGA Tour. Year-end performance statistics for 134 golfers for 2014 appear in the file named LPGA2014 (LPGA website, April 2015). Earn
