For the previous problem, interpret the regression coefficient for labor by estimating the average final cost associated with each dollar that management identified ahead of time as being labor related. Data from Problem 17: Consider the computer output in Table 12.5.12, part of an analysis to explain the final cost of a project based on management’s best guess of labor and materials costs at the time the bid was placed, computed from 25 recent contracts. All variables are measured in dollars. a. What percentage of the variation in cost is explained by the information available at the time the bid is placed? b. Approximately how closely can we predict cost if we know the other variables? c. Find the predicted cost of a project involving $9000 in labor and $20,000 in materials. d. Is the F test significant? What does this tell you? e. Do materials have a significant impact on cost? Table 12.5.12: e/
> What is a variable?
> What is a list of numbers?
> What is the difference between quantitative and qualitative data?
> What is an elementary unit?
> What are qualitative data?
> Distinguish between an observational study and an experiment.
> Continue to view this database as the sample space as in database exercise 1. a. Are the two events “training level A” and “training level B” independent? How do you know? b. Are the two events “training level A” and “training level B” mutually exclusive
> A consultant has just presented a very complicated statistical analysis, complete with lots of mathematical symbols and equations. The results of this impressive analysis go against your intuition and experience. What should you do?
> Differentiate between time-series data and cross sectional data.
> What distinguishes data mining from other statistical methods? What methods, in addition to those of statistics, are often used in data mining?
> What is a data set?
> Why is a confidence interval more useful than an estimated value?
> Why is it worth the effort to learn about statistics? a. Please answer for management in general. b. Please answer for one particular area of business of special interest to you.
> Classify a data set found on the Internet consisting of sales, profits, and number of employees for 100 banking firms. Be sure to provide standard information about the number of variables, who controlled the design of the data-gathering plan, and whethe
> For each of the following data sets, say whether it is primary or secondary data. a. U.S. government data on recent economic activity, by state, being used by a company planning to expand. b. Production-cost data on recent items produced at your firm’s f
> Your firm has decided to sue an unreliable supplier. What kind of analysis would be used to estimate the forgone profit opportunities based on the performance of competitors, the overall state of the economy, and the time of year?
> Which of the five basic activities of statistics is represented by each of the following situations? a. A factory’s quality control division is examining detailed quantitative information about recent productivity in order to identify possible trouble sp
> Continue to view this database as the sample space as in databaseexercise1.Consider the two events“ high experience (6 years or more)” and “female.” a. Find the probabilities of these two events. b. Find the probability of their intersection. What does t
> Consider the histogram in Fig. 3.8.5, which indicates performance of recent on-site service contracts as a rate of return. a. At the very high end, how many contracts were extreme outliers that earned over 900% per year? b. How many contracts are outlier
> What distribution shape is represented by the histogram in Fig. 3.8.4 of hospital length of stay (in days)? Fig. 3.8.4: 20 10 - 0- 10 20 30 40 Days
> What distribution shape is represented by the histogram in Fig. 3.8.3 of volume (in thousands of units) by sales region? Fig. 3.8.3: 40 30 10 10 20 30 40 50 60 70 Volume 20
> What distribution shape is represented by the histogram in Fig. 3.8.2 of profit margins for consumer products? Fig. 3.8.2: 50 40 30 20 10 10 15 20 25 30 Percent 5.
> Your firm’s sales, listed each quarter for the past 5 years, should be helpful for strategic planning. a. Is this data set cross-sectional or time-series? b. Is this univariate, bivariate, or multivariate data?
> In order to figure out how much of the advertising budget to spend on various types of media (TV, radio, newspapers, etc.), you are looking at a data set that lists how much each of your competitors spent last year for TV, how much they spent for radio,
> Table2.6.4 is an excerpt from a sales person’s database of customers. a. What is an elementary unit for this data set? b. What kind of data set is this: Univariate, bivariate, or multivariate? c. Which of these variables are quantitativ
> Table 2.6.3 consists of sales and income, both in hundred thousands of dollars, for a 6-month period. a. What is an elementary unit for this data set? b. What kind of data set is this: Univariate, bivariate, or multivariate? c. Which of these two variabl
> Consider the data set in Table 2.6.2, which consists of observations on five production facilities (identified by their group ID). a. What is an elementary unit for this data set? b. What kind of data set is this: Univariate, bivariate, or multivariate?
> Your company is trying to estimate the total size of its potential market. A survey has been designed, and data have been collected. A histogram of the data shows a small amount of skewness. Which summary measure would you recommend to the company for th
> Please view this database as the sample space of a random experiment in which an employee is selected at random. That is, each employee represents one outcome, and all possible outcomes are equally likely. a.* Find the probability of selecting a female e
> If you think about a telephone directory as a large data set, what are the elementary units?
> What distribution shape is represented by the histogram in Fig. 3.8.1 of voltages measured for incoming components as part of a quality control program? Fig. 3.8.1: 25 20 15 10 5. 100 102 104 106 108 110 112 Volts
> Table 15.5.4 shows the average quality scores for production, averaged according to which supplier (A, B, or C) provided the materials and which shift (day, night, or swing) was active at the time the part was produced; this is followed by the computer v
> Refer to the data for problem 11. Continue using the logarithms of the lengths of calls. a. Find the total sample size, n, the grand average,
> Which time-series method of analysis would be most appropriate to a situation in which prices are lower at harvest time in the fall but are typically higher the rest of the year and in which there is a need for a methodology that is relatively easy to un
> Which time-series method of analysis would be most appropriate to a situation in which forecasts and confidence limits are needed for a data set that shows medium-term cyclic behavior?
> A bank had 38,091 ATM network transactions at its cash machines in January and had 43,182 in February. The seasonal indices are 0.925 for January and 0.986 for February. a. By what percent did ATM transactions increase from January to February? b. By wha
> You have suspected for some time that production problems tend to flare up in the wintertime, during the first quarter of each year. A trend-seasonal analysis of the defect rates indicates seasonal indices of 1.00, 1.01, 1.03, and 0.97 for quarters 1, 2,
> Your seasonally adjusted monthly sales forecast is $382,190+$4,011 (Month number), where the month number is 1 for Jan. 2011 and increases by 1 each month. The seasonal index for February sales is 0.923, and it is 1.137 for April. What you need now is a
> Which type of time-series analysis would provide the simplest results for studying demand for heating oil, which tends to be highest in the winter?
> For the experience variable: Answer the parts of exercise 2. Data from exercise 2: For the annual salary levels: a. Construct a histogram and indicate the average and standard deviation. b. How many employees are within one standard deviation from the
> For each of the following, tell whether or not you would expect it to have a strong seasonal component and why. a. Sales of colorful wrapping paper, recorded monthly. b. The number of air travelers to Hawaii from Chicago, recorded monthly. c. The S&P 500
> For each of the following sentences, say which section (or sections) it might be located in. a.* The scatterplot of defects against the rate of production shows a moderately strong relationship, withacorrelationof0.782, suggesting that our worst problems
> Using your imagination, create an executive summary paragraph for a hypothetical report based on each of the situations in problem 1. (Note: Only one paragraph is required for each situation.) Data from problem 1: Your boss has just asked you to write
> Fill in the blanks, using either affect or effect. a.* The amount of overtime and the time of day had a significant ___________ on accidents in the workplace. b.* The amount of overtime and the time of day significantly ________ accidents in the workplac
> Productivity is a concern. For each employee, you have data on productivity as well as other factors. You want to know how much these factors explain about the variation in productivity from one employee to another. Identify the Y variable, the X variabl
> In order to substantiate a claim of damages, you need to estimate the revenues your firm lost when the opening of the new lumber mill was delayed for three months. You have access to data for similar firms on their total assets, lumber mill capacity, and
> In a multiple regression, what would you suspect is the problem if the R2 is large and significant, but none of the X variables has a t test that is significant?
> Quality control has been a problem with a new product assembly line, and a multiple regression analysis is being used to help identify the source of the trouble. The daily “percent defective” has been identified as the
> It is budgeting time again, and you would like to know the expected payoff (in terms of dollars collected) of spending an extra dollar on collection of delinquent accounts, after adjusting for the size of the pool of delinquent accounts. Identify the Y v
> For the experience variable: Answer the parts of exercise 1. Data from exercise 1: For the annual salary levels: a. Find the range. b. Find the standard deviation. c. Find the coefficient of variation. d. Compare these three summary measures. What do t
> Take a close look at the data using appropriate statistical methods.
> Your firm is wondering about the results of magazine advertising as part of an assessment of marketing strategy. For each ad, you have information on its cost, its size, and the number of inquiries it generated. In particular, you are wondering if the nu
> Identify the structure of the scatterplot in Fig. 11.3.6. Fig. 11.3.6: FIG. 11.3.6
> Identify the structure of the scatterplot in Fig. 11.3.5. Fig. 11.3.5: FIG. 11.3.5
> One weekend when you reduced prices 5%, your store had $58,000 worth of sales. The next weekend, with a 15% reduction, your sales were $92,000. The weekend after that, with a 17.5% reduction, your sales were $95,000. Based on all this information, how mu
> On Monday, your business produced 7 items which cost you $18. On Tuesday, you produced 8 costing $17. On Wednesday, you produced 18 costing $32. On Thursday, you produced 3 items costing $16. Using a linear regression model accounting for fixed and varia
> Which of the following correlation coefficients corresponds to a moderately strong relationship with higher X values associated with higher Y values: r = 1, r = 0.73, r = 0.04, r = –0.83, or r = 0.99?
> One day your factory used $385 worth of electricity to produce 132 items. On a second day, $506 worth of electricity was consumed to produce 183 items. On a third day, the numbers were $261 and 105. How much electricitydoyouestimateitwouldtaketoproduce15
> Given the correlation r = 0.307 and the least-squares prediction equation Y = 55.6+18.2X, find the predicted value for Y when X is $25.
> Given the correlation r = 0.603 and the least-squares prediction equation Y = 38.2–5.3X, find the predicted value for Y when X is 15.
> For each of the scatterplots in Figs. 11.3.1–11.3.4, say whether the correlation is closest to 0.9, 0.5, 0.0, 0.5, or 0.9. Fig. 11.3.1: Fig. 11.3.4: FIG. 11.3.1 FIG. 11.3.4
> For the ages: Answer the parts of exercise 2. Data from exercise 2: For the annual salary levels: a. Construct a histogram and indicate the average and standard deviation. b. How many employees are within one standard deviation from the average? How do
> Find the critical t value that would be used to construct the confidence interval for the slope coefficient in a regression analysis for each of the following situations: a. For 95% confidence, based on a sample size of n = 298. b. For 99% confidence, ba
> The least-squares prediction equation is, predicted costs = 35.2+5.3 (items), with predicted costs measured in dollars. Find the predicted value and residual for a situation with costs of $600 and 100 items.
> a. Why is a two-sided test appropriate for the previous problem? b. State the one-sided result of the two-sided test at the 5% level, if appropriate. Data from Problem 5: Some of your advertisements seem to get no reaction, as though they are being ign
> a. Why is a two-sided test appropriate for the previous problem? b. State the one-sided result of the two-sided test at the 5% level, if appropriate.
> Production yields vary and can be high or low on a given day. If they are high, you want to find out why so that yields could be similarly increased on other days. If they are low, you want to fix the problem. You have just learned that today’s productio
> Here are the satisfaction scores given by 12 randomly selected customers: 89, 98, 96, 65, 99, 81, 76, 51, 82, 90, 96, 76 Does the observed average score differ significantly from the target score of 80? Justify your answer.
> Test whether or not the population percentage could reasonably be 20%, based on the observed 18.4% who like your products, from a random sample of 500 consumers.
> A recent poll of 809 randomly selected registered voters revealed that 426 plan to vote for your candidate in the coming election. a. Is the observed percentage more than 50%? b. Is the observed percentage significantly more than 50%? How do you know? Ba
> Do initial public offerings (IPOs) of stock significantly increase in value, on average, in the short term? Test using the data from Table 4.3.7 that show performance of initial offerings as percent increases from the offer price, with most newly traded
> The p-value is 0.0371. What conclusions can you reach and what error might have been made?
> For the ages: Answer the parts of exercise 1. Data from exercise 1: For the annual salary levels: a. Find the range. b. Find the standard deviation. c. Find the coefficient of variation. d. Compare these three summary measures. What do they tell you ab
> Production yield data with 17 degrees of freedom have been collected. Find the critical t value to use for each of the following confidence interval calculations: a. One-sided 95% confidence. b. One-sided 99% confidence. c. One-sided 99.9% confidence. d.
> Consumer preferences have been observed in a situation for which the standard error is known. Find the critical t value to use for each of the following confidence interval calculations: a. Two-sided 95% confidence. b. Two-sided 99% confidence. c. Two-si
> Vaccine responses have been observed for1,859 people. Find the critical t value to use for each of the following confidence interval calculations: a. Two-sided 95% confidence. b. Two-sided 99% confidence. c. Two-sided 99.9% confidence. d. Two-sided 90% c
> Cost observations have been provided for 21 production situations. Find the critical t value to use for each of the following confidence interval calculations: a. Two-sided 95% confidence. b. Two-sided 99% confidence. c. Two-sided 99.9% confidence. d. Tw
> Intensities have been measured for eight flashlights. Find the critical t value to use for each of the following confidence interval calculations: a. Two-sided 95% confidence. b. Two-sided 99% confidence. c. Two-sided 99.9% confidence. d. Two-sided 90% c
> The amount of caffeine (milligrams) in randomly sampled cups of coffee was as follows: 112:8,86:4, 45:9,110: 3, 100:3,93:3, 101:9,115:7,92:5,117:3,105:6,81:6 a. Find the one-sided 99% confidence interval for the population mean caffeine content of a cup
> From a list of the 729 people who went on a cruise, 130 were randomly selected for interview. Of these, 112 said that they were very happy with the accommodations. Find the 95% confidence interval for the population percentage who would have said they we
> Find the one-sided 95% confidence interval for the weight of candy bars after intervention, based on the data in Table 5.5.4, indicating that the population mean weight is no more than some amount. Table 5.5.4: TABLE 5.5.4 Weight (in Ounces) for Tw
> Find the 99.9% confidence interval for the weight of candy bars before intervention, based on the data in Table 5.5.4 of Chapter 5. Table 5.5.4: TABLE 5.5.4 Weight (in Ounces) for Two Samples of Candy Bars Before Before After After Intervention Int
> Find the 99% confidence interval for the strength of cotton yarn used in a weaving factory based on the data in problem 23 of Chapter 4. Data from problem 23: Consider the strength of cotton yarn used in a weaving factory, in pounds of force at breakag
> For the annual salary levels: a. Construct a histogram and indicate the average and standard deviation. b. How many employees are within one standard deviation from the average? How does this compare to what you would expect for a normal distribution? c.
> Find the 95% confidence interval for the amounts that your regular customers spent on your products last month, viewing the data from Table 4.3.1 of Chapter 4 as a random sample of customer orders. Table 4.3.1: TABLE 4.3.1 Last Month's Sales Custom
> Your quality control department has just analyzed the contents of 20 randomly selected barrels of materials to be used in manufacturing plastic garden equipment. The results found an average of 41.93 gallons of usable material per barrel, with a standard
> A market survey has shown that people will spend an average of $2.34 each for your product next year, based on a sample survey of 400 people. The standard deviation of the sample was $0.72. Find the two-sided 95% confidence interval for next year’s mean
> Your hospital is negotiating with medical insurance providers, who would like to reduce the amount they pay as reimbursement for hospital stays. For a particular procedure, they would like to reduce payment by $300 and have patients go home one day earli
> Based on the following daily percent changes of the S&P 500 stock market index for June 2010 (accessed at http:// finance.Yahoo.com on July 13,2010), find the 95% confidence interval for the population mean daily change. (This is not, strictly speaking,
> Comparison shopping is available on the Internet, and this is useful because exactly the same item is available at a variety of prices. Table 9.6.1 shows results from My Simon for prices of the Eureka 4750A Bagged Upright Vacuum at 15 stores. Find the 95
> Your firm is in the market to hire an experienced vice president of information technology or information systems. If one is chosen at random from the population represented in the preceding problem, complete the following sentence: We are 99% sure that
> A survey of eight vice presidents of information technology and information systems, who had been in their current positions for 10 years or less, revealed $174,813 as the average salary.15 Assume a random sample with a standard deviation of $25,000. a.
> A survey of 21 business intelligence analysts, who had been in their current positions from 10 to 20 years, revealed $90,734 as the average salary.14 Assume a random sample with a standard deviation of $15,000. a. Find the 95% confidence interval for the
> A nationwide poll claims that the margin of error is no more than 4.3 percentage points for questions asked of half the sample (at the 95% confidence level). a. Verify this claim in a particular case by computing the critical t value times the standard e
> For the annual salary levels: a. Find the range. b. Find the standard deviation. c. Find the coefficient of variation. d. Compare these three summary measures. What do they tell you about typical salaries in this administrative division?
> A nationwide poll claims that the margin of error is no more than 3 percentage points in either direction (ie, plus or minus) at the 95% confidence level. a. Verify this claim in a particular case by computing the critical t value times the standard erro
> In a sample of 258 individuals selected randomly from a city of 750,339 people, 165 were found to be supportive of a new public works project. Find the99.9%confidence interval for the support level percentage in the entire city.
> A recent survey of 252 customers, selected at random from a database with 12,861 customers, found that 208 are satisfied with the service they are receiving. Find the 99% confidence interval for the percentage satisfied for all customers in the database.
> Your company prepares and distributes frozen foods. The package claims a net weight of 24.5 oz. A random sample of today’s production was weighed, and the results were summarized as follows: average = 24.41 oz, standard deviation = 0.11 oz, sample size =
> Your company is planning to market a new reading lamp and has segmented the market into three groups: avid readers, regular readers, and occasional readers. As part of a marketing survey, 400 individuals have been randomly selected from the population of
