Assume that the normality requirement in Exercise 16.7 is not met. Test to determine whether the price of a condominium and floor number are positively related.
> Research scientists at a pharmaceutical company have recently developed a new nonprescription sleeping pill. They decide to test its effectiveness by measuring the time it takes for people to fall asleep after taking the pill. Preliminary analysis indica
> a. Data from a matched pairs experiment were recorded. Use the sign test to determine whether the population locations differ. b. Repeat Part (a) using the Wilcoxon signed rank sum test. c. Why do the results of Parts (a) and (b) differ?
> a. Data from a matched pairs experiment were recorded. Use the sign test to determine whether the population locations differ. b. Repeat Part (a) using the Wilcoxon signed rank sum test. c. Why do the answers to Parts (a) and (b) differ?
> a. A random sample of 50 people was asked to rate two brands of ice cream using the following responses: Delicious OK Not bad Terrible The responses were converted to codes 4, 3, 2, and 1, respectively. Can we infer that Brand A is preferred? b. The resp
> a. In a taste test of a new beer 100 people rated the new beer and the leading brand on the market. The possible ratings were Poor, Fair, Good, Very good, and Excellent. The responses for the new beer and the leading beer were recorded using a 1-2-3-4-5
> Perform the Wilcoxon signed rank sum test to determine whether the location of population 1 differs from the location of population 2 given the data shown here. (Use  = .05.) 1 2 3 4 5 6 7 8 9 10 11 12 Sample 1 18.2 14.1 245 11.9 9
> Perform the Wilcoxon signed rank sum test for the following matched pairs to determine whether the two population locations differ. (Use  = .10.) Pair 1 3 4 5 6. Sample 1 Sample 2 9 12 13 8 7 10 10 11 9 3 9
> A matched pairs experiment produced the following statistics. Conduct a Wilcoxon signed rank sum test to determine whether the location of population 1 is to the right of the location of population 2. (Use = .01.) T+ = 3,457 T− = 2,429 n = 108
> Betting on the results of National Football League games is a popular North American activity. In some states and provinces, it is legal to do so provided that wagers are made through a government-authorized betting organization. In the province of Ontar
> Use the Wilcoxon Rank Sum Test on the following data to determine whether the two population locations differ. (Use a 10% significance level.) Sample 1: 15 7 22 20 32 18 26 17 23 30 Sample 2: 8 27 17 25 20 16 21 17 10 18
> Given the following statistics from a matched pairs experiment, perform the Wilcoxon signed rank sum test to determine whether we can infer at the 5% significance level that the two population locations differ. T+ = 660 T− = 880 n = 55
> Use the sign test on the following data to determine whether the location of population 1 is to the right of the location of population 2. (Use  = .05.) Pair: 12 3 4 5 6 789 10 11 12 13 14 15 16 Sample 1 5 3 4 2 3 4 3 5 4 3 4 5 4 5
> A matched pairs experiment yielded the following results: Positive differences: 18 Zero differences: 0 Negative differences: 12 Can we infer at the 5% significance level that the location of population 1 is to the right of the location of population 2?
> Suppose that in a matched pairs experiment we find 28 positive differences, 7 zero differences, and 41 negative differences. Can we infer at the 10% significance level that the location of population 1 is to the left of the location of population 2?
> In a matched pairs experiment, if we find 30 negative, 5 zero, and 15 positive differences, perform the sign test to determine whether the two population locations differ. (Use a 5% significance level.)
> Use the Wilcoxon Rank Sum Test on the following data to determine whether the location of population 1 is to the left of the location of population 2. (Use  = .05.) Sample 1: 75 60 73 66 81 Sample 2: 90 72 103 82 78
> These problems can be solved manually or by creating an Excel spreadsheet. a. From the following statistics, test (with = .05) to determine whether the location of population 1 is to the right of the location of population 2. t1 = 1,205 n1 = 30 t2 = 1
> Burger King Restaurants regularly survey customers to determine how well they are doing. Suppose that a survey asked customers to rate (among other things) the speed of service. The responses are 1 = Poor 2 = Good 3 = Very good 4 = Excellent The response
> Do the ways that women dress influence the ways that other women judge them? This question was addressed by a researcher at Ohio State University (Working Mother, April 1992). The experiment consisted of asking women to rate how professional two women lo
> There are enormous differences between health-care systems in the United States and Canada. In a study to examine one dimension of these differences, 300 heart attack victims in each country were randomly selected. (Results of the study conducted by Dr.
> Can you become addicted to exercise? In a study conducted at the University of Wisconsin at Madison, a random sample of dedicated exercisers who usually work out every day was drawn. Each completed a questionnaire that gauged their mood on a 5-point scal
> How does alcohol affect judgment? To provide some insight, an experiment was conducted. A random sample of customers of an Ohio club was selected. Each respondent was asked to assess the attractiveness of members of the opposite sex who were in the club
> According to a CNN news report 9% of full-time workers telecommute. This means that they do not work in their employers’ offices but instead perform their work at home using a computer and modem. To ascertain whether such workers are more satisfied than
> It is an unfortunate fact of life that the characteristics that one is born with play a critical role in later life. For example, race is a critical factor in almost all aspects of North American life. Height and weight also determine how friends, teache
> How does gender affect teaching evaluations? Several researchers addressed this question during the past decade. In one study several female and male professors in the same department with similar backgrounds were selected. A random sample of 100 female
> Scientists have been studying the effects of lead in children’s blood, bones, and tissue for a number of years. It is known that lead reduces intelligence and can cause a variety of other problems. A study directed by Dr. Herman Needleman, a psychiatrist
> The town of Stratford, Ontario, is very much dependent on the Shakespearean Festival it holds every summer for its financial well-being. Thousands of people visit Stratford to attend one or more Shakespearean plays and spend money in hotels, restaurants,
> To examine the effect that a tough midterm test has on student evaluations of professors, a statistics professor had her class evaluate her teaching effectiveness before the midterm test. The questionnaire asked for opinions on a number of dimensions, bu
> The increasing number of traveling businesswomen represents a large potential clientele for the hotel industry. Many hotel chains have made changes designed to attract more women. To help direct these changes, a hotel chain commissioned a study to determ
> It is common practice in many MBA programs to require applicants to arrange for a letter of reference. Some universities have their own forms in which referees assess the applicant using the following categories: 5: The candidate is in the top 5% of appl
> Several years ago we heard about the “Mommy Track,” the phenomenon of women being underpaid in the corporate world because of what is seen as their divided loyalties between home and office. There may also be a “Daddy Differential,” which refers to the s
> The president of Tastee Inc., a babyfood producer, claims that her company’s product is superior to that of her leading competitor because babies gain weight faster with her product. As an experiment, 40 healthy newborn infants are randomly selected. For
> In a Gallup poll this year, 200 people were asked, “Do you feel that the newspaper you read most does a good job of presenting the news?” The same question was asked of another 200 people 10 years ago. The possible responses were as follows: 3 = Good job
> Researchers at the U.S. National Institute of Aging in Bethesda, Maryland, have been studying hearing loss. They have hypothesized that as men age they will lose their hearing faster than comparably aged women because many more men than women have worked
> An advertising firm wants to determine the relative effectiveness of two recently produced commercials for a car dealership. An important attribute of such commercials is their believability. To judge this aspect of the commercials, 60 people were random
> Samuel’s is a chain of family restaurants. Like many other service companies, Samuel’s surveys its customers on a regular basis to monitor their opinions. Two questions (among others) asked in the survey are as follows: a. While you were at Samuel’s, did
> In recent years, consumers have become more safety conscious, particularly about children’s products. A manufacturer of children’s pajamas is looking for material that is as nonflammable as possible. In an experiment to compare a new fabric with the kind
> The printing department of a publishing company wants to determine whether there are differences in durability between three types of book bindings. Twenty-five books with each type of binding were selected and placed in machines that continually opened
> Suppose that a precise measuring device for new hair growth has been developed and is used in the experiment described in Exercise 19.122. The percentages of new hair growth for the 30 pairs of men involved in the experiment were recorded. Do these data
> Large potential profits for pharmaceutical companies exist in the area of hair growth drugs. The head chemist for a large pharmaceutical company is conducting experiments to determine which of two new drugs is more effective in growing hair among balding
> The editor of the student newspaper was in the process of making some major changes in the newspaper’s layout. He was also contemplating changing the typeface of the print used. To help make a decision, he set up an experiment in which 20 individuals wer
> A new antiflu vaccine designed to reduce the duration of symptoms has been developed. However, the effect of the drug varies from person to person. To examine the effect of age on the effectiveness of the drug, a sample of 140 flu sufferers was drawn. Ea
> The researchers at a large carpet manufacturer have been experimenting with a new dyeing process in hopes of reducing the streakiness that frequently occurs with the current process. As an experiment, 15 carpets are dyed using the new process, and anothe
> Certain drugs differ in their side effects depending on the gender of the patient. In a study to determine whether men or women suffer more serious side effects when taking a powerful penicillin substitute, 50 men and 50 women were given the drug. Each w
> In a study to determine which of two teaching methods is perceived to be better, two sections of an introductory marketing course were taught in different ways by the same professor. At the course’s completion, each student rated the course on a boring/s
> Are education and income related? To answer this question, a random sample of peoplewas selected and each was asked to indicate into which of the following categories of education they belonged: 1. Less than high school 2. High school graduate 3. Some co
> The American public’s support for the space program is important for the program’s continuation and for the financial health of the aerospace industry. In a poll conducted by the Gallup organization last year, a random sample of 100 Americans was asked,
> Gambling on sports is big business in the United States and Canada. A television executive wants to know whether the amount of money wagered on a professional football game affects the enjoyment of viewers. A random sample of 200 men who regularly watch
> explain that after they quit smoking food tastes better. To examine the relationship between smoking and taste, a researcher randomly sampled 280 smokers. Each was asked how many cigarettes they smoked on an average day. In addition, each person was aske
> Assume that the conditions for the test conducted in Exercise 16.6 are not met. Do the data allow us to conclude that the longer the commercial, the higher the memory test score will be?
> Many people suffer from heartburn. It appears, however, that the problem may increase with age. A researcher for a pharmaceutical company wanted to determine whether age and the incidence and extent of heartburn are related. A random sample of 325 adults
> Do cell phones cause cancer? This is a multibillion- dollar question. Currently, dozens of lawsuits are pending that claim cell phone use has caused cancer. To help shed light on the issue, several scientific research projects have been undertaken. One s
> Slow play of golfers is a serious problem for golf clubs. Slow play results in fewer rounds of golf and less profits for public course owners. To examine this problem, a random sample of British and American golf courses was selected. The amount of time
> At the completion of most courses in universities and colleges, a course evaluation is undertaken. Some professors believe that the way in which students fill out the evaluations is based on how well the student is doing in the course. To test this theor
> Refer to Example 16.2. If the required condition is not satisfied conduct another more appropriate test to determine whether odometer reading and price are related. Data from Example 16.2:
> Feminist organizations often use the issue of who does the housework in two-career families as a gauge of equality. Suppose that a study was undertaken and a random sample of 125 two-career families was taken. The wives were asked to report the number of
> These problems can be solved manually or by creating an Excel spreadsheet. a. Given the following statistics calculate the value of the test statistic to determine whether the population locations differ. t1 = 250 n1 = 15 t2 = 215 n2 = 15 b. Repeat par
> For Exercises 20.7 and 20.8, draw the time series and the two sets of exponentially smoothed values. Does there appear to be a trend component in the time series?
> Repeat Exercise 20.7 with w = .8.
> Apply exponential smoothing with w = .1 to help detect the components of the following time series. Period 1 2 3 4 5 Time Series 12 18 16 24 17 Period 6 7 8 9. 10 Time Series 16 25 21 23 14
> For Exercises 20.4 and 20.5, graph the time series and the two moving averages.
> The number of housing starts (in 1,000s) in the northeast United States for the years 2004 to 2009 were recorded. a. Use the 2004–2008 data to calculate the seasonal indexes. b. Use the indexes and regression analysis to forecast the number of housing st
> Using the seasonal indexes and trend line, forecast revenues for the next four quarters.
> An article in the journal Appetite (December 2003) described an experiment to determine the effect that breakfast meals have on school children. A sample of 29 children was tested on four successive days, having a different breakfast each day. The breakf
> Determine the seasonal indexes.
> For Exercise 20.4, compute the five-period moving averages.
> Use regression analysis to determine the trend line.
> Discuss why exponential smoothing is not recommended as a forecasting tool in this problem.
> Apply the trend line and seasonal indexes from Exercise 20.29 to forecast accounts receivable for the next four quarters.
> Refer to Exercise 20.28. Use the seasonal indexes and trend line to forecast the number of pizzas to be sold for each of the next 7 days. Data from Exercise 20.28: The owner of a pizzeria wants to forecast the number of pizzas she will sell each day. Sh
> Use the seasonal indexes and trend line from Exercise 20.27 to forecast the number of cable subscribers for the next four quarters.
> Refer to Exercise 20.26. Forecast next year’s merchandise trade balance using the following methods. a. Autoregressive forecasting model. b. Exponential smoothing method with w = .7. Data from Exercise 20.26: Foreign trade is important to the United Sta
> Refer to Exercise 20.25. Forecast next year’s enrollment using the following methods. a. Autoregressive forecasting model. b. Exponential smoothing method with w = .5. Data from Exercise 20.25: College and university enrollment increased sharply during
> Use the seasonal indexes and trend line to forecast the quarterly earnings for the years 2014 and 2015 in Exercise 20.24.
> In the last decade, society in general and the judicial system in particular have altered their opinions on the seriousness of drunken driving. In most jurisdictions, driving an automobile with a blood alcohol level in excess of .08 is a felony. Because
> Refer to Exercise 20.23. Use the seasonal indexes and the trend line to forecast the time series for the next four quarters. Data from Exercise 20.23: Given the following time series, compute the seasonal indexes. The regression equation is y^ = 47.7 −
> For the following time series, compute the three-period moving averages. Period Time Series Period Time Series 1 16 7 24 2 22 8 29 3 19 9 21 4 24 10 23 5 30 11 19 15 6. 26 12
> Use the seasonal indexes and trend line to forecast the time series for the next 5 days in Exercise 20.22.
> Apply exponential smoothing with w = .4 to forecast the next four quarters in Exercise 20.15.
> The following autoregressive equation was developed. Forecast the next value if the last observed value was 11. y^ = 155 + 21yt−1
> Use the following autoregressive equation to forecast the next value of the time series if the last observed value is 65. y^ = 625 − 1.3yt−1
> The following trend line and seasonal indexes were computed from 4 weeks of daily observations. Forecast the 7 values for next week. y^ = 120 + 2.3t t = 1, 2, . . . , 28 Day Seasonal Index Sunday Monday Tuesday Wednesday Thursday Friday Saturday 1.5
> The following trend line and seasonal indexes were computed from 10 years of quarterly observations. Forecast the next year’s time series. y^ = 150 + 3t t = 1, 2, . . . , 40 Quarter Seasonal Index 1 .7 2 1.2 3 1.5 .6
> Three forecasting techniques were used to predict the values of a time series. These values are given in the following table. Compute MAD and SSE for each technique to determine which was most accurate. Period 1 4 Forecast (Model 1) 21 27 29 31 35 Fo
> Calculate MAD and SSE for the forecasts that follow. Period 1 2 4 Forecast 63 72 86 71 60 Actual 57 60 70 75 70 3.
> The marketing manager of a large ski resort wants to advertise that his ski resort has the shortest lift lines of any resort in the area. To avoid the possibility of a false advertising liability suit, he collects data on the times skiers wait in line at
> Two forecasting models were used to predict the future values of a time series. These are shown here together with the actual values. Compute MAD and SSE for each model to determine which was more accurate. Period 2 3 4 Forecast (Model 1) 7.5 6.3 5.4
> For the actual and forecast values of a time series shown here, calculate MAD and SSE Period 1 2 4 5 Forecast 173 186 192 211 223 Actual Value 166 179 195 214 220 LO 3.
> For Exercises 20.1 and 20.2, graph the time series and the two moving averages.
> A manufacturer of ski equipment is in the process of reviewing his accounts receivable. He noticed that there appears to be a seasonal pattern with the accounts receivable increasing in the winter months and decreasing during the summer. The quarterly ac
> The owner of a pizzeria wants to forecast the number of pizzas she will sell each day. She recorded the numbers sold daily for the past 4 weeks. Calculate the seasonal (daily) indexes.
> The number of cable television subscribers has increased over the past 5 years. The marketing manager for a cable company has recorded the numbers of subscribers for the past 24 quarters. a. Plot the numbers. b. Compute the seasonal (quarterly) indexes.
> Foreign trade is important to the United States. No country exports and imports more. However, there has been a large trade imbalance in many sectors. To measure the extent of the problem, an economist recorded the difference between exports and imports
> College and university enrollment increased sharply during the 1970s and 1980s. However, since then, the rate of growth has slowed. To help forecast future enrollments, an economist recorded the total U.S. college and university enrollment from 1993 to 2
> The quarterly earnings (in $millions) of a large soft-drink manufacturer have been recorded for the years 2013–2016. These data are listed here. Compute the seasonal indexes given the regression line y^ = 61.75 + 1.18t (t = 1, 2, . . .
> Given the following time series, compute the seasonal indexes. The regression equation is y^ = 47.7 − 1.06t (t = 1, 2, . . . , 20) Year Quarter 1 2 3 4 5 1 55 41 43 36 50 2 44 38 39 32 25 3 46 37 39 30 24 4 39 30 35 25 22
> Researchers at the University of Washington conducted an experiment to determine whether the herbal remedy Echinacea is effective in treating children’s colds and other respiratory infection (National Post, December 3, 2003). A sample of 524 children wer
> For the following time series, compute the seasonal (daily) indexes. The regression line is y^ = 16.8 + .366t (t = 1, 2, . . . , 20) Week Day 1 2 3 4 Monday Tuesday Wednesday Thursday Friday 12 11 14 17 18 17 16 21 16 19 16 20 25 24 28 24 31 27 25 32
> Refer to Exercise 20.19. Use regression analysis to calculate the linear and quadratic trends. Which line fits better? Data from Exercise 20.19: Plot the following time series to determine which of the trend models appears to fit better.
> Refer to Exercise 20.18. Use regression analysis to calculate the linear and quadratic trends. Which line fits better? Data from Exercise 20.18: Plot the following time series. Would the linear or quadratic model fit better?
