Classroom Activity: Estimating the Proportion of the Earth's Surface That Is Covered by Water

• Activity Number: 518
• Type: Contributed
• Date/Time: Wednesday, August 6, 2014 : 10:30 AM to 12:20 PM
• Sponsor: Section on Statistical Education
• Author(s): Paul Stephenson*+ and Laura Kapitula
• Companies: Grand Valley State University and Grand Valley State University
• Keywords: Confidence intervals ; Estimating proportions ; Geospatial random sampling ; Classroom activities ; Demonstrating confidence levels

Abstract

One of the most commonly employed statistical methods for reporting public opinion is the confidence interval for the population proportion. Examples include the proportion of Americans who approve of the President, the percentage of drivers who text while driving, and the prevalence of a disease in a wildlife species. Consequently, a sound understanding of the process and methods used to construct a confidence interval for a population proportion is important. In this presentation the authors will discuss how a random sample of locations across the planet can be used to estimate the proportion of the Earth's surface covered by water. In addition, we will introduce a website that efficiently generates the random locations and allows students to employ Google Maps to inspect the each location. In conclusion, we will demonstrate how we used a classroom activity, entitled "How Wet is the Earth?," to explore the construction of a confidence interval for the proportion, the concepts of confidence level and margin of error, and the impact of sample size on width of the resulting interval.