What Proportion Of The U.S. Is Within A Mile Of A Road?

Abstract

A challenge in introductory statistics is to motivate the estimation of unknown population parameters. In this activity, we allow students to estimate the proportion of the continental United States that is within a mile of a road by repeatedly sampling latitudes and longitudes and viewing that location using an internet mapping service. Technology is used to generate random values within a specified geographic rectangle, which populate a data collection spreadsheet. Students are instructed how to use MapQuest.com to determine if the random location is within the continental US and if so, whether it is within a mile of a road. This data collection task helps to fix ideas of study design ("what if the point lands in the middle of one of the Great Lakes"?) as well as motivate the estimation of an unknown proportion. Individual confidence intervals can be created and compared, as well as creation of a class-wide confidence interval. This activity can be used in introductory classes at all levels.