Recall that phishing describes an attempt to extract personal/financial information from unsuspecting people through fraudulent e-mail. The interarrival times (in seconds) for 267 fraud box e-mail notifications are saved in the accompanying file. Like with Exercise 5.23, consider these interarrival times to represent the population of interest.
a. Obtain a random sample of n = 10 interarrival times from the population.
b. Use the sample, part b, to obtain an interval estimate of the population variance of the interarrival times. What is the measure of reliability for your estimate?
c. Find the true population variance for the data. Does the interval, part b, contain the true variance? Give one reason why it may not.
For Information: Refer to the Chance (Summer 2007) study of an actual phishing attack against an PHISH organization, Exercise 5.23.