In "Compliance with the Item Limit of the Food Supermarket Express Checkout Lane: An Informal Look," researcher J. Trinkaus reported, "75 15-min observations of customers' behavior at a food supermarket showed that only about 15% of shoppers observed the item limit of the express lane."20
a. Is 15% a statistic or a parameter? Should it be denoted p or ?
b. Can we tell the approximate count of shoppers who observed the item limit? If so, what is it? If not, explain why not.
c. Which type of sample is suggested by the word informal: volunteer, random, convenience, or stratified?
d. If these results are used to estimate that about 15% of all shoppers observe the item limit of the express lane, are we performing data production, displaying and summarizing data, probability, or inference?