EXAMPLE 5.1

Understanding the college student market. Since 1987, Student Monitor has published an annual market research study that provides clients with information about the college student market. The firm uses a random sample of 1200 students located throughout the United States.¹ One phase of the research focuses on computing and technology. The firm reports that undergraduates spend an average of 19.0 hours per week on the Internet and that 88% own a cell phone.

The sample mean hours is a statistic. The corresponding parameter is the average (call it μ) of all undergraduates enrolled in four-year colleges and universities. Similarly, the proportion of the samplesample proportion who own a cell phone

is a statistic. The corresponding parameter is the proportionpopulation proportion (call it p) of all undergraduates at four-year colleges and universities who own a cell phone. We don’t know the values of the parameters μ and p, so we use the statistics and , respectively, to estimate them.