What is statistics?
> When is the best time to write the introduction and executive summary, first or last? Why?
> Continuing with the sample from exercise 2: a.* Find the binomial X for the gender variable (counting the number of females) and interpret it. b.* Find the standard error of X and interpret it. c. Find the population mean for the binomial X. d. How far i
> What can you do to help those in your audience who are short of time?
> What is the primary purpose of writing a report?
> Describe the two measures that tell you how helpful a multiple regression analysis is.
> Why should variables measured in the same basic units be transformed in the same way?
> Which activity (correlation or regression analysis) is involved in each of the following situations? a. Investigating to see whether there is any measurable connection between advertising expenditures and sales. b. Developing a system to predict portfoli
> Distinguish correlation and regression analysis.
> What is extrapolation? Why is it especially troublesome?
> a. Which is usually better, a lower or a higher value for R2? b. Which is better, a lower or a higher value for Se?
> For each of the following situations tell whether the predicted value or the residual would be most useful. a. For budgeting purposes you need to know what number to place under “cost of goods sold” based on the expected sales figure for the next quarter
> What can be done with multivariate data?
> Do exercise 3 using the experiences instead of the salaries. Data from exercise 3: Continuing with the sample from the preceding exercise: a. Find the population mean for salary. (Note: In real life, you usually cannot find the population mean. We are
> Are Kellerman’s conclusions correct?
> What is new and different about analysis of bivariate data compared to univariate data?
> Suppose you learn that the p- value for a hypothesis test is equal to 0.0217. What can you say about the result of this test?
> What standard error would you use to test whether a new observation came from the same population as a sample? (Give both its name and the formula.)
> Suppose you have an estimator and would like to test whether or not the population mean value equals 0. What do you need in addition to the estimated value?
> What p-value statement is associated with each of the following outcomes of a hypothesis test? a. Not significant. b. Significant. c. Highly significant. d. Very highly significant.
> a. What confidence levels other than 95% are in common use? b. What would you do differently to compute a 99% confidence interval instead of a 95% interval? c. Which is larger, a two-sided 90% confidence interval or a two-sided 95% confidence interval?
> Why are critical t values generally larger than1.960 for a two-sided 95% confidence interval?
> Why is it correct to say, “We are 95% sure that the population mean is between $15.85 and $19.36” but not proper to say, “The probability is 0.95 that the population mean is between $15.85 and $19.36”?
> Which fact about a normal distribution leads to the factor 2 (or 1.960) in the approximate confidence interval statement?
> What does a confidence interval tell you about the population that an estimated value alone does not?
> Do exercise 3 using the ages instead of the salaries. Data from exercise 3: Continuing with the sample from the preceding exercise: a. Find the population mean for salary. (Note: In real life, you usually cannot find the population mean. We are peeking
> In what way do bivariate data represent more than just two separate univariate data sets?
> In what important way does statistical inference go beyond summarizing the data?
> a. What is the sampling distribution of a statistic? b. What is the standard deviation of a statistic?
> a. What is a statistic? b. What is a parameter?
> What is a frame? What is its role in sampling?
> What do the standard errors Sx and Sp indicate for a binomial situation?
> a. What is the complement of an event? b. What is the probability of the complement of an event?
> What are mutually exclusive events?
> a. What is an event? b. Can a random experiment have more than one event of interest?
> a. What is an outcome? b. Must the outcome be a number?
> Do exercise 2 using the experiences instead of the salaries. Data from exercise 2: Draw a random sample without replacement of 10 employees, using the table of random digits, starting in row 23, column 7. a.* List the employee numbers for your sample.
> a. What is a sample space? b. Is there anything random or uncertain about a sample space?
> What is the design phase of a statistical study?
> What is a joint probability table?
> a. What is the coefficient of variation? b. What are the measurement units of the coefficient of variation?
> If your data set is normally distributed, what proportion of the individuals do you expect to find: a. Within one standard deviation from the average? b. Within two standard deviations from the average? c. Within three standard deviations from the averag
> a. What is a deviation from the average? b. What is the average of all of the deviations?
> a. What is the traditional measure of variability? b. What other measures are also used?
> When a fixed number is added to each data value, what happens to a. The average, median, and mode? b. The standard deviation and range? c. The coefficient of variation?
> Which variability measure is most useful for comparing variability in two different situations, adjusting for the fact that the situations have very different average sizes? Justify your choice.
> What is variability?
> Do exercise 2 using the ages instead of the salaries. Data from exercise 2: Draw a random sample without replacement of 10 employees, using the table of random digits, starting in row 23, column 7. a.* List the employee numbers for your sample. b. Find
> What is the mode?
> How do you find the median for a data set: a. With an odd number of values? b. With an even number of values?
> What is the median? How can it be found from its rank?
> What is meant by a typical value for a list of numbers? Name three different ways of finding one.
> How should you deal with exceptions when summarizing a set of data?
> What is a box plot? What additional detail is often included in a box plot?
> What is the five-number summary?
> What are the quartiles?
> Name two ways in which percentiles are used.
> Continuing with the sample from the preceding exercise: a. Find the population mean for salary. (Note: In real life, you usually cannot find the population mean. We are peeking “behind the scenes” here.) b. Compare this population mean to the sample aver
> Which summary measure is best for a. A normal distribution? b. Projecting total amounts? c. A skewed distribution when totals are not important?
> Which summary measure(s) may be used on a. Nominal data? b. Ordinal data? c. Quantitative data?
> What is summarization of a data set? Why is it important?
> How should statistical analysis and business experience interact with each other?
> What is a skewed distribution?
> Are all data sets normally distributed?
> When a real data set is normally distributed, should you expect the histogram to be a perfectly smooth bell shaped curve? Why or why not?
> Why is the normal distribution important in statistics?
> What is a normal distribution?
> What is a number line?
> Draw a random sample without replacement of 10 employees, using the table of random digits, starting in row 23, column 7. a.* List the employee numbers for your sample. b. Find the average salary for yours sample and interpret this number. c. Find the st
> Suppose there is an outlier in your data. You plan to analyze the data twice: once with and once without the outlier. What result would you be most pleased with? Why?
> When is it appropriate to set aside an outlier and analyze only the rest of the data?
> What is an outlier?
> How can you interpret the logarithm of a number?
> 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
