There are many simple data-collection exercises that can be performed with the goal of estimating a population mean for a particular problem. We encourage you to perform your own. The parts below discuss some possible data collection ideas that would result in count data. For each part, outline how to take a sample and discuss any simplifying assumptions that may be needed in order to apply the statistical methods from this chapter. Collect the data and examine the appropriateness of the Poisson distribution by comparing the sample mean to the sample variance and comparing observed relative frequencies and the corresponding probabilities from a Po() distribution.
(a) Observe the number of people standing in line at a grocery store checkout(s).
(b) Examine the number of Ph.D. graduates from a university's academic department.
(c) Count the number of cars passing through an intersection of streets over a period of time.