At the beginning of this chapter, on page 332, we presented b. Find and interpret a 95% confidence interval for the mean summary statistics for data on bank robberies for five variables: amount stolen. amount stolen, number of bank staff present, number of customers c. Find and interpret a 95% confidence interval for the mean present, number of bank raiders, and travel time from the bank to number of bank staff present at the time of robberies. the nearest police station. These summary statistics were obtained d. Determine and interpret a 95% confidence interval for the by three researchers for data from a sample of 364 bank raids over mean number of customers present at the time of robberies. a several-year period in the United Kingdom. For all bank raids e. Determine and interpret a 95% confidence interval for the in the United Kingdom during the years in question: mean number of bank raiders. a. Identify and interpret a point estimate for the mean of each of f. Obtain and interpret a 95% confidence interval for the mean the five aforementioned variables. travel time from the nearest police station to the bank outlet. CASE STUDY Bank Robberies: A Statistical Analysis The researchers concentrated on the factors that determine the amount of proceeds from bank robberies, at thus were able to work out bolt the economics of attempting one and of preventing one. In particular, the researchers revealed that the return on an average bank robbery per person per raid is modest indeed-so Variable Mean | Std. dev. modest that it is not worthwhile for the banks to spend too much Amount stolen (pounds sterling) 20,330.5 53,510.2 A 587 money on such preventative Number of bank staff present 5.417 4.336 measures as fast-rising screens Number of customers present 2.000 3.684 at tellers' windows. Number of bank raiders 1.637 0.971 The researchers obtained Travel time, in minutes from bank In the article "Robbing Banks" exclusive data from the British to nearest police station 4.557 4.028 (Significance, Vol. 9, Issue 3, Bankers' Association. In one aspect pp. 17-21) B. Reilly et al. studied of their study, they analyzed the several aspects of bank robberies. data from a sample of 364 bank After studying point estimates and summary statistics to estimate the As these researchers state, raids over a several-year period in confidence intervals in this chapter, (population) means of the variables "Robbing a bank is the staple crime the United Kingdom. The following you will be asked to use these in the table. of thrillers, movies and newspapers. table repeats a portion of Table 1 But . . . bank robbery is not all it is on page 19 of the article. cracked up to be."